156

156 is the natural number that follows 155 and precedes 157. In mathematics, it is an even composite number with prime factorization 2^2 × 3 × 13. Its divisors are 1, 2, 3, 4, 6, 12, 13, 26, 39, 52, 78, and 156. The sum of its proper divisors is 236, which exceeds 156, making 156 an abundant number. The total sum of all divisors is 392. The number is also a Harshad (or Niven) number in base 10, since 156 is divisible by the sum of its digits (1 + 5 + 6 = 12), giving 156 ÷ 12 = 13.

In various numeral systems, 156 is represented as follows: decimal 156, binary 10011100, octal 234, hexadecimal 9C, and Roman numerals CLVI.

From a number-theoretic perspective, 156 is not a prime and is not a sum of two squares, because its prime factorization includes 3, a prime congruent to 3 modulo 4, with an odd exponent. It is also not a triangular number, since the equation n(n+1)/2 = 156 has no integer solution.

Culturally or historically, 156 appears primarily as a boundary or identifier in cataloging, labeling, and arithmetic examples rather than as a notable constant with wide-ranging named properties.