256187640 has 64 divisors (see below), whose sum is σ = 809020800. Its totient is φ = 64720512.

The previous prime is 256187563. The next prime is 256187641. The reversal of 256187640 is 46781652.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256187641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 53902 + ... + 58461.

It is an arithmetic number, because the mean of its divisors is an integer number (12640950).

Almost surely, 2^256187640 is an apocalyptic number.

256187640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256187640 is an abundant number, since it is smaller than the sum of its proper divisors (552833160).

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

256187640 is a wasteful number, since it uses less digits than its factorization.

256187640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 112396 (or 112392 counting only the distinct ones).

The product of its (nonzero) digits is 80640, while the sum is 39.

The square root of 256187640 is about 16005.8626759072. The cubic root of 256187640 is about 635.1155182816.

The spelling of 256187640 in words is "two hundred fifty-six million, one hundred eighty-seven thousand, six hundred forty".