157

157 is: the 37th prime number. The next prime is 163 and the previous prime is 151. a balanced prime, because the arithmetic mean of those primes yields 157. an emirp. a Chen prime. the largest known prime p which p p + 1 p + 1 {\displaystyle {\frac {p^{p}+1}{p+1}}} is also prime. (see OEIS: A056826). the least irregular prime with index 2. a palindromic number in bases 7 (3137) and 12 (11112). a repunit in base 12, so it is a unique prime in the same base. a prime whose digits sum to a prime. a prime index prime.