644420724 has 24 divisors (see below), whose sum is σ = 1504849248. Its totient is φ = 214635360.

The previous prime is 644420681. The next prime is 644420731. The reversal of 644420724 is 427024446.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5307 + ... + 36290.

It is an arithmetic number, because the mean of its divisors is an integer number (62702052).

Almost surely, 2^644420724 is an apocalyptic number.

It is an amenable number.

644420724 is an abundant number, since it is smaller than the sum of its proper divisors (860428524).

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

644420724 is a wasteful number, since it uses less digits than its factorization.

644420724 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42895 (or 42893 counting only the distinct ones).

The product of its (nonzero) digits is 43008, while the sum is 33.

The square root of 644420724 is about 25385.4431515386. The cubic root of 644420724 is about 863.7535251590.

The spelling of 644420724 in words is "six hundred forty-four million, four hundred twenty thousand, seven hundred twenty-four".