645740856 has 32 divisors (see below), whose sum is σ = 1793725200. Its totient is φ = 215246880.

The previous prime is 645740831. The next prime is 645740863. The reversal of 645740856 is 658047546.

It is a super-2 number, since 2×645740856² = 833962506215225472, which contains 22 as substring.

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, 1494555 + ... + 1494986.

Almost surely, 2^645740856 is an apocalyptic number.

It is an amenable number.

645740856 is an abundant number, since it is smaller than the sum of its proper divisors (1147984344).

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

645740856 is a wasteful number, since it uses less digits than its factorization.

645740856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2989556 (or 2989546 counting only the distinct ones).

The product of its (nonzero) digits is 806400, while the sum is 45.

The square root of 645740856 is about 25411.4316007580. The cubic root of 645740856 is about 864.3429387085.

The spelling of 645740856 in words is "six hundred forty-five million, seven hundred forty thousand, eight hundred fifty-six".