639659328 has 224 divisors, whose sum is σ = 2155545600. Its totient is φ = 165957120.

The previous prime is 639659309. The next prime is 639659333. The reversal of 639659328 is 823956936.

It is a tau number, because it is divible by the number of its divisors (224).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 723975 + ... + 724857.

Almost surely, 2^639659328 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639659328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1077772800).

639659328 is an abundant number, since it is smaller than the sum of its proper divisors (1515886272).

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

639659328 is a wasteful number, since it uses less digits than its factorization.

639659328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 930 (or 906 counting only the distinct ones).

The product of its digits is 2099520, while the sum is 51.

The square root of 639659328 is about 25291.4872635043. The cubic root of 639659328 is about 861.6209414625.

The spelling of 639659328 in words is "six hundred thirty-nine million, six hundred fifty-nine thousand, three hundred twenty-eight".