644660984 has 16 divisors (see below), whose sum is σ = 1318624920. Its totient is φ = 293027680.

The previous prime is 644660971. The next prime is 644660987. The reversal of 644660984 is 489066446.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644660987) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3662759 + ... + 3662934.

Almost surely, 2^644660984 is an apocalyptic number.

It is an amenable number.

644660984 is an abundant number, since it is smaller than the sum of its proper divisors (673963936).

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

644660984 is a wasteful number, since it uses less digits than its factorization.

644660984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7325710 (or 7325706 counting only the distinct ones).

The product of its (nonzero) digits is 995328, while the sum is 47.

The square root of 644660984 is about 25390.1749501653. The cubic root of 644660984 is about 863.8608565079.

The spelling of 644660984 in words is "six hundred forty-four million, six hundred sixty thousand, nine hundred eighty-four".