644837872 has 20 divisors (see below), whose sum is σ = 1427855536. Its totient is φ = 276359040.

The previous prime is 644837849. The next prime is 644837891. The reversal of 644837872 is 278738446.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2878629 + ... + 2878852.

Almost surely, 2^644837872 is an apocalyptic number.

It is an amenable number.

644837872 is an abundant number, since it is smaller than the sum of its proper divisors (783017664).

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

644837872 is a wasteful number, since it uses less digits than its factorization.

644837872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5757496 (or 5757490 counting only the distinct ones).

The product of its digits is 1806336, while the sum is 49.

The square root of 644837872 is about 25393.6581059130. The cubic root of 644837872 is about 863.9398606403.

The spelling of 644837872 in words is "six hundred forty-four million, eight hundred thirty-seven thousand, eight hundred seventy-two".