5231 is a Sophie Germain prime. A prime number p is a Sophie Germain prime if 2p + 1 is also prime. 5231 is a Sophie Germain prime because 2 x 5231 + 1 = 10463 is also prime. Sophie Germain primes are mentioned in the stage play Proof and the subsequent film.
Sophie Germain (1716-1831)
5231 and 5233 form a twin prime pair.
5231 is a number that cannot be written as a sum of three squares.
5231 is a prime where all the digits except the last one are prime.