256466640 has 40 divisors (see below), whose sum is σ = 795047328. Its totient is φ = 68391040.

The previous prime is 256466621. The next prime is 256466671. The reversal of 256466640 is 46664652.

It is a tau number, because it is divible by the number of its divisors (40).

It is a Smith number, since the sum of its digits (39) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 534066 + ... + 534545.

Almost surely, 2^256466640 is an apocalyptic number.

256466640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256466640 is an abundant number, since it is smaller than the sum of its proper divisors (538580688).

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

256466640 is a wasteful number, since it uses less digits than its factorization.

256466640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1068627 (or 1068621 counting only the distinct ones).

The product of its (nonzero) digits is 207360, while the sum is 39.

The square root of 256466640 is about 16014.5758607588. The cubic root of 256466640 is about 635.3459912052.

The spelling of 256466640 in words is "two hundred fifty-six million, four hundred sixty-six thousand, six hundred forty".