256819640 has 64 divisors (see below), whose sum is σ = 720437760. Its totient is φ = 80046720.

The previous prime is 256819639. The next prime is 256819681. The reversal of 256819640 is 46918652.

It is a happy number.

It is a hoax number, since the sum of its digits (41) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38612 + ... + 44771.

It is an arithmetic number, because the mean of its divisors is an integer number (11256840).

Almost surely, 2^256819640 is an apocalyptic number.

256819640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256819640 is an abundant number, since it is smaller than the sum of its proper divisors (463618120).

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

256819640 is a wasteful number, since it uses less digits than its factorization.

256819640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83412 (or 83408 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 41.

The square root of 256819640 is about 16025.5932807494. The cubic root of 256819640 is about 635.6373537457.

The spelling of 256819640 in words is "two hundred fifty-six million, eight hundred nineteen thousand, six hundred forty".