639878688 has 72 divisors (see below), whose sum is σ = 1878379776. Its totient is φ = 206409600.

The previous prime is 639878683. The next prime is 639878689. The reversal of 639878688 is 886878936.

It is a tau number, because it is divible by the number of its divisors (72).

It is not an unprimeable number, because it can be changed into a prime (639878683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 26908 + ... + 44763.

It is an arithmetic number, because the mean of its divisors is an integer number (26088608).

Almost surely, 2^639878688 is an apocalyptic number.

It is an amenable number.

639878688 is an abundant number, since it is smaller than the sum of its proper divisors (1238501088).

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

639878688 is a wasteful number, since it uses less digits than its factorization.

639878688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71718 (or 71707 counting only the distinct ones).

The product of its digits is 27869184, while the sum is 63.

The square root of 639878688 is about 25295.8235287962. The cubic root of 639878688 is about 861.7194228260.

The spelling of 639878688 in words is "six hundred thirty-nine million, eight hundred seventy-eight thousand, six hundred eighty-eight".