44

This number is a composite.

The sum of the first emirp pair: 13 + 31. [Rivera]

44^4*4 + 1 is prime. [Honaker]

44 is the first number such that it and the next number are the product of a prime and another distinct prime squared (44 = 2^2*11 and 45 = 3^2*5). [Axoy]