158

158 = 2 x 79.

158 is the maximum number of regions into which 13 circles divide the plane.

158 is the smallest number such that the sum of the number and its reverse is a nonpalindromic prime: 158 + 851 = 1009, and 1009 is a nonpalindromic prime.

158 is the sum of the first nine Mersenne prime exponents: 2 + 3 + 5 + 7 + 13 + 17 + 19 + 31 + 61 = 158.

Episode 158 (Season 8) of The Simpsons is titled "Bart after Dark" and features a mock-up of the Beatles album cover "Sgt. Pepper's Lonely Hearts Club Band."

Source: Number Gossip