644844672 has 64 divisors (see below), whose sum is σ = 1903197600. Its totient is φ = 214947072.

The previous prime is 644844661. The next prime is 644844709. The reversal of 644844672 is 276448446.

644844672 is a `hidden beast` number, since 64 + 484 + 46 + 72 = 666.

It is a tau number, because it is divible by the number of its divisors (64).

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, 89838 + ... + 96749.

Almost surely, 2^644844672 is an apocalyptic number.

It is an amenable number.

644844672 is an abundant number, since it is smaller than the sum of its proper divisors (1258352928).

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

644844672 is a wasteful number, since it uses less digits than its factorization.

644844672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186610 (or 186592 counting only the distinct ones).

The product of its digits is 1032192, while the sum is 45.

The square root of 644844672 is about 25393.7919972579. The cubic root of 644844672 is about 863.9428974607.

The spelling of 644844672 in words is "six hundred forty-four million, eight hundred forty-four thousand, six hundred seventy-two".