640447764 has 24 divisors (see below), whose sum is σ = 1630231008. Its totient is φ = 194075040.

The previous prime is 640447741. The next prime is 640447771. The reversal of 640447764 is 467744046.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2425807 + ... + 2426070.

It is an arithmetic number, because the mean of its divisors is an integer number (67926292).

Almost surely, 2^640447764 is an apocalyptic number.

It is an amenable number.

640447764 is an abundant number, since it is smaller than the sum of its proper divisors (989783244).

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

640447764 is a wasteful number, since it uses less digits than its factorization.

640447764 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4851895 (or 4851893 counting only the distinct ones).

The product of its (nonzero) digits is 451584, while the sum is 42.

The square root of 640447764 is about 25307.0694470932. The cubic root of 640447764 is about 861.9748038063.

The spelling of 640447764 in words is "six hundred forty million, four hundred forty-seven thousand, seven hundred sixty-four".