644823320 has 16 divisors (see below), whose sum is σ = 1450852560. Its totient is φ = 257929312.

The previous prime is 644823301. The next prime is 644823337. The reversal of 644823320 is 23328446.

644823320 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×644823320² = 831594228031644800, which contains 22 as substring.

It is a congruent number.

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, 8060252 + ... + 8060331.

It is an arithmetic number, because the mean of its divisors is an integer number (90678285).

Almost surely, 2^644823320 is an apocalyptic number.

It is an amenable number.

644823320 is an abundant number, since it is smaller than the sum of its proper divisors (806029240).

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

644823320 is a wasteful number, since it uses less digits than its factorization.

644823320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16120594 (or 16120590 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 32.

The square root of 644823320 is about 25393.3715760629. The cubic root of 644823320 is about 863.9333617729.

The spelling of 644823320 in words is "six hundred forty-four million, eight hundred twenty-three thousand, three hundred twenty".