155

155 = 5 x 31.

155 has the representation 155 = 2⁷ + 27.

155 = 2² + 3! + 5! + 7² -11 - 13.

155 is the only three-digit number such that 155¹⁵⁵ - 155 + 1 is prime.

155 is the sum of its prime factors plus the primes between these two prime factors: 155 = 5 + 7 + 11 + 13 + 17 + 19 + 23 + 29 + 31.

155 = 3³ + 4³ + 4³.

155 = 5¹ + 5² + 5³.

Source: Prime Curios!