256611640 has 16 divisors (see below), whose sum is σ = 577376280. Its totient is φ = 102644640.

The previous prime is 256611631. The next prime is 256611643. The reversal of 256611640 is 46116652.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256611643) 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, 3207606 + ... + 3207685.

Almost surely, 2^256611640 is an apocalyptic number.

256611640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256611640 is an abundant number, since it is smaller than the sum of its proper divisors (320764640).

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

256611640 is a wasteful number, since it uses less digits than its factorization.

256611640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6415302 (or 6415298 counting only the distinct ones).

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 256611640 is about 16019.1023468857. The cubic root of 256611640 is about 635.4657050368.

The spelling of 256611640 in words is "two hundred fifty-six million, six hundred eleven thousand, six hundred forty".