256939440 has 160 divisors (see below), whose sum is σ = 842088960. Its totient is φ = 64677888.

The previous prime is 256939429. The next prime is 256939453. The reversal of 256939440 is 44939652.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 256939392 and 256939401.

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 31 ways as a sum of consecutive naturals, for example, 491019 + ... + 491541.

It is an arithmetic number, because the mean of its divisors is an integer number (5263056).

Almost surely, 2^256939440 is an apocalyptic number.

256939440 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256939440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (421044480).

256939440 is an abundant number, since it is smaller than the sum of its proper divisors (585149520).

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

256939440 is a wasteful number, since it uses less digits than its factorization.

256939440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 651 (or 645 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 42.

The square root of 256939440 is about 16029.3306160925. The cubic root of 256939440 is about 635.7361747412.

The spelling of 256939440 in words is "two hundred fifty-six million, nine hundred thirty-nine thousand, four hundred forty".