644032264 has 16 divisors (see below), whose sum is σ = 1237013820. Its totient is φ = 314161920.

The previous prime is 644032247. The next prime is 644032273. The reversal of 644032264 is 462230446.

It can be written as a sum of positive squares in 2 ways, for example, as 617920164 + 26112100 = 24858^2 + 5110^2 .

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, 981429 + ... + 982084.

Almost surely, 2^644032264 is an apocalyptic number.

It is an amenable number.

644032264 is a deficient number, since it is larger than the sum of its proper divisors (592981556).

644032264 is a wasteful number, since it uses less digits than its factorization.

644032264 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1963560 (or 1963556 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 31.

The square root of 644032264 is about 25377.7907627910. The cubic root of 644032264 is about 863.5799319743.

The spelling of 644032264 in words is "six hundred forty-four million, thirty-two thousand, two hundred sixty-four".