639988578 has 24 divisors (see below), whose sum is σ = 1387776000. Its totient is φ = 213155064.

The previous prime is 639988553. The next prime is 639988607. The reversal of 639988578 is 875889936.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9123 + ... + 36921.

It is an arithmetic number, because the mean of its divisors is an integer number (57824000).

Almost surely, 2^639988578 is an apocalyptic number.

639988578 is an abundant number, since it is smaller than the sum of its proper divisors (747787422).

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

639988578 is a wasteful number, since it uses less digits than its factorization.

639988578 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29086 (or 29083 counting only the distinct ones).

The product of its digits is 26127360, while the sum is 63.

The square root of 639988578 is about 25297.9955332433. The cubic root of 639988578 is about 861.7687493254.

The spelling of 639988578 in words is "six hundred thirty-nine million, nine hundred eighty-eight thousand, five hundred seventy-eight".