639888 has 20 divisors (see below), whose sum is σ = 1653168. Its totient is φ = 213280.

The previous prime is 639857. The next prime is 639907. The reversal of 639888 is 888936.

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, 6618 + ... + 6713.

2⁶³⁹⁸⁸⁸ is an apocalyptic number.

It is an amenable number.

639888 is an abundant number, since it is smaller than the sum of its proper divisors (1013280).

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

639888 is a wasteful number, since it uses less digits than its factorization.

639888 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13342 (or 13336 counting only the distinct ones).

The product of its digits is 82944, while the sum is 42.

The square root of 639888 is about 799.9299969372. The cubic root of 639888 is about 86.1723602937.

The spelling of 639888 in words is "six hundred thirty-nine thousand, eight hundred eighty-eight".