In mathematics, an interprime is the average of two consecutive odd primes.[1] For example, 9 is an interprime because it is the average of 7 and 11. The first interprimes are:
Interprimes cannot be prime themselves (otherwise the primes would not have been consecutive).[1]
Since there are infinitely many primes, there are also infinitely many interprimes. The largest known interprime as of 2018[update] may be the 388342-digit n = 2996863034895 · 21290000, where n + 1 is the largest known twin prime.[2]