646656440 has 64 divisors (see below), whose sum is σ = 1475496000. Its totient is φ = 255044608.

The previous prime is 646656433. The next prime is 646656487. The reversal of 646656440 is 44656646.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1079261 + ... + 1079859.

It is an arithmetic number, because the mean of its divisors is an integer number (23054625).

Almost surely, 2^646656440 is an apocalyptic number.

It is an amenable number.

646656440 is an abundant number, since it is smaller than the sum of its proper divisors (828839560).

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

646656440 is a wasteful number, since it uses less digits than its factorization.

646656440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 944 (or 940 counting only the distinct ones).

The product of its (nonzero) digits is 414720, while the sum is 41.

The square root of 646656440 is about 25429.4404185385. The cubic root of 646656440 is about 864.7512577347.

The spelling of 646656440 in words is "six hundred forty-six million, six hundred fifty-six thousand, four hundred forty".