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22 (number)

Summary

22 (twenty-two) is the natural number following 21 and preceding 23.

 ← 21 22 23 →
Cardinaltwenty-two
Ordinal22nd
(twenty-second)
Factorization2 × 11
Divisors1, 2, 11, 22
Greek numeralΚΒ´
Roman numeralXXII
Binary101102
Ternary2113
Octal268
Duodecimal1A12

In mathematics

The first 22 numbers can be arranged on a graph such that select sums between two numbers in the set yield all primes from 3 to 43. The graph has near-perfect vertical and horizontal reflective symmetry.[1]

22 is an even composite number and the eighth semiprime;[2] its proper divisors are 1, 2, and 11.

22 is:

Furthermore,

• ${\displaystyle {\frac {22}{7}}}$  is a commonly used approximation of the irrational number π, the ratio of the circumference of a circle to its diameter; where both 22 and 7 are consecutive hexagonal pyramidal numbers. 22 also features in another approximation for pi, here by Srinivasa Ramanujan from an approximate construction of the squaring of the circle, and correct to eight decimal digits:[16]
${\displaystyle {\sqrt[{4}]{\frac {2143}{22}}}=3.141\;592\;65{\color {red}2\;582\;\ldots }}$

• The 22nd unique prime in base ten is notable for having starkly different digits compared to its preceding (and latter) unique primes, as well as for the similarity of its digits to those of the reciprocal of 7.[20] Being 84 digits long, and having a period length of 294 digits, it is the number:
${\displaystyle 142,857,157,142,857,142,856,999,999,985,714,285,714,285,857,142,857,142,855,714,285,571,428,571,428,572,857,143}$

In aircraft

• 22 is the designation of the USAF stealth fighter, the F-22 Raptor.

In sports

• In both American football and association football, a total of 22 players (counting both teams) start the game, and this is also the maximum number of players that can be legally involved in play at any given time.
• In Australian rules football, each team is allowed a squad of 22 players (18 on the field and 4 interchanges).
• The length of a cricket pitch is 22 yards.
• In rugby union, the "22" is a line in each half of the field which is 22 meters from the respective try line. It has significance in a number of laws particularly relating to kicking the ball away.
• A snooker game (called a "frame") starts with 22 coloured balls at specified locations on the table (15 red balls and 7 others).

In other uses

Twenty-two may also refer to:

References

1. ^ Barton, James. "The Number 22: Properties and Meanings". VirtualScience. Retrieved 2022-04-17.
2. ^ Weisstein, Eric W. "Semiprime". mathworld.wolfram.com. Retrieved 2020-08-12.
3. ^ Sloane, N. J. A. (ed.). "Sequence A002113 (Palindromes in base 10)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-04-16.
4. ^ Weisstein, Eric W. "Deficient Number". mathworld.wolfram.com. Retrieved 2020-08-12.
5. ^ Sloane, N. J. A. (ed.). "Sequence A001608 (Perrin sequence)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-31.
6. ^ Sloane, N. J. A. (ed.). "Sequence A006753 (Smith numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-31.
7. ^ Sloane, N. J. A. (ed.). "Sequence A059756 (Erdős-Woods numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-31.
8. ^ Sloane, N. J. A. (ed.). "Sequence A000326 (Pentagonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-31.
9. ^ Sloane, N. J. A. (ed.). "Sequence A002412 (Hexagonal pyramidal numbers, or greengrocer's numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-04-16.
10. ^ Sloane, N. J. A. (ed.). "Sequence A069099 (Centered heptagonal numbers)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-31.
11. ^ Sloane, N. J. A. (ed.). "Sequence A002088 (Sum of totient function)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-31.
12. ^ Sloane, N. J. A. (ed.). "Sequence A000010 (Euler totient function phi(n))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-04-16.
13. ^ Sloane, N. J. A. (ed.). "Sequence A014206". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-04-16.
14. ^ Wells, D. The Penguin Dictionary of Curious and Interesting Numbers London: Penguin Group. (1986): 31
15. ^ Sloane, N. J. A. (ed.). "Sequence A000124 (Central polygonal numbers (the Lazy Caterer's sequence))". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-31.
16. ^ Ramanujan, S. (1914). "Modular equations and approximations to π" (PDF). Quarterly Journal of Mathematics. 45: 350–372.
17. ^ Martin, Oscar (2006). "Look-and-Say Biochemistry: Exponential RNA and Multistranded DNA" (PDF). American Mathematical Monthly. Mathematical association of America. 113 (4): 289–307. doi:10.2307/27641915. ISSN 0002-9890. JSTOR 27641915. Archived from the original (PDF) on 2006-12-24. Retrieved 2018-11-21.
18. ^ Coxeter, H.S.M. (1991), Regular Complex Polytopes, Cambridge University Press, p. 140, ISBN 0-521-39490-2
19. ^ Tilings and Patterns Branko Gruenbaum, G.C. Shephard, 1987. 2.5 Tilings using star polygons, pp.82-85.
20. ^ Sloane, N. J. A. (ed.). "Sequence A040017 (Unique period primes)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2022-05-20.
21. ^ Twenty Two - Karma to Burn | Song Info | AllMusic, retrieved 2020-08-12
22. ^ Twenty Two - The Vicar | Song Info | AllMusic, retrieved 2020-08-12
23. ^ Twenty Two - Jordan Sweeney | Song Info | AllMusic, retrieved 2020-08-12
24. ^ Twenty Two - The Good Life | Song Info | AllMusic, retrieved 2020-08-12
25. ^ Twenty Two - Sweet Nectar | Song Info | AllMusic, retrieved 2020-08-12
26. ^ Twenty Two - American Generals | Song Info | AllMusic, retrieved 2020-08-12
27. ^ Twenty Two - Dan Anderson | Song Info | AllMusic, retrieved 2020-08-12
28. ^ Twenty Two - Bad Cash Quartet | Song Info | AllMusic, retrieved 2020-08-12
29. ^ Twenty Two - Millencolin | Song Info | AllMusic, retrieved 2020-08-12
30. ^ Twenty Two - Enter the Worship Circle | Song Info | AllMusic, retrieved 2020-08-12
31. ^ Twenty Two - Blank Dogs | Song Info | AllMusic, retrieved 2020-08-12
32. ^ Twenty Two - Al Candello | Song Info | AllMusic, retrieved 2020-08-12
33. ^ Twenty Two - Amen Dunes | Song Info | AllMusic, retrieved 2020-08-12
34. ^ 22 Two's - Jay-Z | Song Info | AllMusic, retrieved 2020-08-12
35. ^ 22 Acacia Avenue - Iron Maiden | Song Info | AllMusic, retrieved 2020-08-12
36. ^ Catch 22 - Hypocrisy | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-12
37. ^ 22 Dreams - Paul Weller | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-12
38. ^ "Ugress | Album Discography". AllMusic. Retrieved 2020-08-12.
39. ^ Cinematronics - Ugress | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-12
40. ^ Unicorn - Ugress | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-12
41. ^ Twenty Two - The Vicar | Song Info | AllMusic, retrieved 2020-08-12
42. ^ Number 22 - Ashbury Heights | Song Info | AllMusic, retrieved 2020-08-12
43. ^ 22, A Million - Bon Iver | Songs, Reviews, Credits | AllMusic, retrieved 2020-08-12
44. ^ "Cubic 22 | Songs". AllMusic. Retrieved 2020-08-12.
45. ^ 22 - Deaf Havana | Song Info | AllMusic, retrieved 2020-08-12
46. ^ 22 - Sarah McTernan | Song Info | AllMusic, retrieved 2020-08-12
47. ^ "Definition of CATCH-22". www.merriam-webster.com. Retrieved 2020-08-12.
48. ^ "Paramount Pictures' Logo Started as a Desktop Doodle, and Has Endured for 105 Years". Retrieved 2020-08-12.
49. ^ González-Wippler, Migene (1991). The Complete Book of Amulets & Talismans. Llewellyn Worldwide. p. 87. ISBN 978-0-87542-287-9.
50. ^ Sharp, Damian (2001). Simple Numerology: A Simple Wisdom book (A Simple Wisdom Book series). Red Wheel. p. 7. ISBN 978-1573245609.
51. ^ "Definition of CHAIN". www.merriam-webster.com. Retrieved 2020-08-19. a unit of length equal to 66 feet
52. ^ Cuartas, Javier (1990-01-05). "La suerte de los dos patitos" [The luck of the two little ducks]. El País (in Spanish). Oviedo. Retrieved 17 September 2020.
53. ^ Sanz, Elena (26 April 2010). "Los dos patitos, la niña bonita, la mala pata..." Muy Interesante (in Spanish). Retrieved 17 September 2020. Lo más normal es que el nombre tuviera que ver con la forma del número. Por ejemplo, el 11 era las banderillas, y el 22, los dos patitos o las monjas arrodilladas.