644902964 has 12 divisors (see below), whose sum is σ = 1129593024. Its totient is φ = 322162104.

The previous prime is 644902963. The next prime is 644902967. The reversal of 644902964 is 469209446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644902963) 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, 67292 + ... + 76275.

It is an arithmetic number, because the mean of its divisors is an integer number (94132752).

Almost surely, 2^644902964 is an apocalyptic number.

It is an amenable number.

644902964 is a deficient number, since it is larger than the sum of its proper divisors (484690060).

644902964 is a wasteful number, since it uses less digits than its factorization.

644902964 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144694 (or 144692 counting only the distinct ones).

The product of its (nonzero) digits is 373248, while the sum is 44.

The square root of 644902964 is about 25394.9397321592. The cubic root of 644902964 is about 863.9689292810.

The spelling of 644902964 in words is "six hundred forty-four million, nine hundred two thousand, nine hundred sixty-four".