256416640 has 32 divisors (see below), whose sum is σ = 612997560. Its totient is φ = 102566400.

The previous prime is 256416617. The next prime is 256416653. The reversal of 256416640 is 46614652.

It is a tau number, because it is divible by the number of its divisors (32).

It is a junction number, because it is equal to n+sod(n) for n = 256416596 and 256416605.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 199686 + ... + 200965.

Almost surely, 2^256416640 is an apocalyptic number.

256416640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

256416640 is an abundant number, since it is smaller than the sum of its proper divisors (356580920).

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

256416640 is an equidigital number, since it uses as much as digits as its factorization.

256416640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 400670 (or 400658 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 34.

The square root of 256416640 is about 16013.0147067940. The cubic root of 256416640 is about 635.3047001115.

The spelling of 256416640 in words is "two hundred fifty-six million, four hundred sixteen thousand, six hundred forty".