256005631 has 4 divisors (see below), whose sum is σ = 292577872. Its totient is φ = 219433392.

The previous prime is 256005619. The next prime is 256005641. The reversal of 256005631 is 136500652.

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-256005631 is a prime.

It is a super-2 number, since 2×256005631² = 131077766207416322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 256005631.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256005641) 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, 18286110 + ... + 18286123.

It is an arithmetic number, because the mean of its divisors is an integer number (73144468).

Almost surely, 2^256005631 is an apocalyptic number.

256005631 is a deficient number, since it is larger than the sum of its proper divisors (36572241).

256005631 is an equidigital number, since it uses as much as digits as its factorization.

256005631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36572240.

The product of its (nonzero) digits is 5400, while the sum is 28.

The square root of 256005631 is about 16000.1759677824. The cubic root of 256005631 is about 634.9650763028.

The spelling of 256005631 in words is "two hundred fifty-six million, five thousand, six hundred thirty-one".