157 (number)

157 (one hundred [and] fifty-seven) is the number following 156 and preceding 158.

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 ${\displaystyle {\frac {p^{p}+1}{p+1}}}$ 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. (see OEIS: A046704).
• a prime index prime.

In base 10, 157² is 24649, and 158² is 24964, which uses the same digits. Numbers having this property are listed in OEIS: A072841. The previous entry is 13, and the next entry after 157 is 913.

The simplest right angle triangle with rational sides that has area 157 has the longest side with a denominator of 45 digits.

• "157" is a song by Tom Rosenthal where the lyrics merely consist of the numbers from 1 to 157. The song was released on April Fools' Day, 2020.

Wikimedia Commons has media related to 157 (number).

• The Number 157
• Prime Curios: 157