256631840 has 24 divisors (see below), whose sum is σ = 606293100. Its totient is φ = 102652672.

The previous prime is 256631839. The next prime is 256631863. The reversal of 256631840 is 48136652.

It can be written as a sum of positive squares in 2 ways, for example, as 249513616 + 7118224 = 15796^2 + 2668^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 256631840.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 801815 + ... + 802134.

Almost surely, 2^256631840 is an apocalyptic number.

256631840 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256631840 is an abundant number, since it is smaller than the sum of its proper divisors (349661260).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

256631840 is a wasteful number, since it uses less digits than its factorization.

256631840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1603964 (or 1603956 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 35.

The square root of 256631840 is about 16019.7328317297. The cubic root of 256631840 is about 635.4823788328.

The spelling of 256631840 in words is "two hundred fifty-six million, six hundred thirty-one thousand, eight hundred forty".