329891

This number is a prime.

An illustration of Wilson's theorem for the case n=11: ((11-1)!+1)/11=329891, an integer, therefore 11 is prime. [McCandless]

Prime number p such that p = ((2k)!+1)/(2k+1), where k being both a Sophie Germain prime (2k+1) and a Mersenne prime (2^k-1). Here, k = 5. [Kasa]