639131688 has 64 divisors (see below), whose sum is σ = 1911940800. Its totient is φ = 196655040.

The previous prime is 639131687. The next prime is 639131699. The reversal of 639131688 is 886131936.

It is a happy number.

639131688 is a `hidden beast` number, since 639 + 1 + 3 + 1 + 6 + 8 + 8 = 666.

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (639131687) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 110998 + ... + 116613.

It is an arithmetic number, because the mean of its divisors is an integer number (29874075).

Almost surely, 2^639131688 is an apocalyptic number.

It is an amenable number.

639131688 is an abundant number, since it is smaller than the sum of its proper divisors (1272809112).

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

639131688 is a wasteful number, since it uses less digits than its factorization.

639131688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 227639 (or 227629 counting only the distinct ones).

The product of its digits is 186624, while the sum is 45.

The square root of 639131688 is about 25281.0539337267. The cubic root of 639131688 is about 861.3839659797.

The spelling of 639131688 in words is "six hundred thirty-nine million, one hundred thirty-one thousand, six hundred eighty-eight".