256405131 has 6 divisors (see below), whose sum is σ = 370362980. Its totient is φ = 170936748.

The previous prime is 256405111. The next prime is 256405139. The reversal of 256405131 is 131504652.

256405131 is a `hidden beast` number, since 2 + 5 + 640 + 5 + 13 + 1 = 666.

It is not a de Polignac number, because 256405131 - 2⁷ = 256405003 is a prime.

It is a super-2 number, since 2×256405131² = 131487182406254322, 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 = 256405095 and 256405104.

It is not an unprimeable number, because it can be changed into a prime (256405139) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 14244721 + ... + 14244738.

Almost surely, 2^256405131 is an apocalyptic number.

256405131 is a deficient number, since it is larger than the sum of its proper divisors (113957849).

256405131 is a wasteful number, since it uses less digits than its factorization.

256405131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28489465 (or 28489462 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 256405131 is about 16012.6553388250. The cubic root of 256405131 is about 635.2951949676.

Adding to 256405131 its reverse (131504652), we get a palindrome (387909783).

The spelling of 256405131 in words is "two hundred fifty-six million, four hundred five thousand, one hundred thirty-one".