ソフィー・ジェルマン素数
It is a prime number. The next is 241, with which it forms a pair of twin primes; hence, it is also a Chen prime. 239 is a Sophie Germain prime and a Newman–Shanks–Williams prime. It is an Eisenstein prime with no imaginary part and real part of the form 3"n" − 1 (with no exponentiation implied). 239 is also a happy number.