639884 has 12 divisors (see below), whose sum is σ = 1279824. Its totient is φ = 274224.

The previous prime is 639857. The next prime is 639907. The reversal of 639884 is 488936.

639884 is an admirable number.

It is an unprimeable number.

639884 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11399 + ... + 11454.

It is an arithmetic number, because the mean of its divisors is an integer number (106652).

2⁶³⁹⁸⁸⁴ is an apocalyptic number.

It is an amenable number.

639884 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

639884 is a wasteful number, since it uses less digits than its factorization.

639884 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22864 (or 22862 counting only the distinct ones).

The product of its digits is 41472, while the sum is 38.

The square root of 639884 is about 799.9274967145. The cubic root of 639884 is about 86.1721807362.

The spelling of 639884 in words is "six hundred thirty-nine thousand, eight hundred eighty-four".