644605564 has 24 divisors (see below), whose sum is σ = 1183210560. Its totient is φ = 306916416.

The previous prime is 644605553. The next prime is 644605573. The reversal of 644605564 is 465506446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39379 + ... + 53290.

It is an arithmetic number, because the mean of its divisors is an integer number (49300440).

Almost surely, 2^644605564 is an apocalyptic number.

It is an amenable number.

644605564 is a deficient number, since it is larger than the sum of its proper divisors (538604996).

644605564 is a wasteful number, since it uses less digits than its factorization.

644605564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 92757 (or 92755 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 40.

The square root of 644605564 is about 25389.0835596719. The cubic root of 644605564 is about 863.8361010981.

The spelling of 644605564 in words is "six hundred forty-four million, six hundred five thousand, five hundred sixty-four".