256531 has 4 divisors (see below), whose sum is σ = 279864. Its totient is φ = 233200.

The previous prime is 256517. The next prime is 256541. The reversal of 256531 is 135652.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 256531 - 2⁵ = 256499 is a prime.

It is a super-2 number, since 2×256531² = 131616307922, which contains 22 as substring.

It is a Duffinian number.

It is a zygodrome in base 3.

It is not an unprimeable number, because it can be changed into a prime (256541) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11650 + ... + 11671.

It is an arithmetic number, because the mean of its divisors is an integer number (69966).

2²⁵⁶⁵³¹ is an apocalyptic number.

256531 is a deficient number, since it is larger than the sum of its proper divisors (23333).

256531 is a wasteful number, since it uses less digits than its factorization.

256531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23332.

The product of its digits is 900, while the sum is 22.

The square root of 256531 is about 506.4888942514. The cubic root of 256531 is about 63.5399133202.

It can be divided in two parts, 256 and 531, that added together give a palindrome (787).

The spelling of 256531 in words is "two hundred fifty-six thousand, five hundred thirty-one".