256131731 has 4 divisors (see below), whose sum is σ = 256404864. Its totient is φ = 255858600.

The previous prime is 256131713. The next prime is 256131763. The reversal of 256131731 is 137131652.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256131731 is a prime.

It is a super-2 number, since 2×256131731² = 131206927250112722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 256131694 and 256131703.

It is not an unprimeable number, because it can be changed into a prime (256131791) 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, 135155 + ... + 137036.

It is an arithmetic number, because the mean of its divisors is an integer number (64101216).

Almost surely, 2^256131731 is an apocalyptic number.

256131731 is a deficient number, since it is larger than the sum of its proper divisors (273133).

256131731 is an equidigital number, since it uses as much as digits as its factorization.

256131731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 273132.

The product of its digits is 3780, while the sum is 29.

The square root of 256131731 is about 16004.1160643130. The cubic root of 256131731 is about 635.0693135324.

The spelling of 256131731 in words is "two hundred fifty-six million, one hundred thirty-one thousand, seven hundred thirty-one".