644563716 has 12 divisors (see below), whose sum is σ = 1503982032. Its totient is φ = 214854568.

The previous prime is 644563697. The next prime is 644563727. The reversal of 644563716 is 617365446.

It is a tau number, because it is divible by the number of its divisors (12).

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, 26856810 + ... + 26856833.

It is an arithmetic number, because the mean of its divisors is an integer number (125331836).

Almost surely, 2^644563716 is an apocalyptic number.

It is an amenable number.

644563716 is an abundant number, since it is smaller than the sum of its proper divisors (859418316).

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

644563716 is a wasteful number, since it uses less digits than its factorization.

644563716 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53713650 (or 53713648 counting only the distinct ones).

The product of its digits is 362880, while the sum is 42.

The square root of 644563716 is about 25388.2594125710. The cubic root of 644563716 is about 863.8174071879.

The spelling of 644563716 in words is "six hundred forty-four million, five hundred sixty-three thousand, seven hundred sixteen".