639642760 has 32 divisors (see below), whose sum is σ = 1440172800. Its totient is φ = 255683520.

The previous prime is 639642721. The next prime is 639642779. The reversal of 639642760 is 67246936.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 65815 + ... + 74905.

It is an arithmetic number, because the mean of its divisors is an integer number (45005400).

Almost surely, 2^639642760 is an apocalyptic number.

It is an amenable number.

639642760 is an abundant number, since it is smaller than the sum of its proper divisors (800530040).

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

639642760 is a wasteful number, since it uses less digits than its factorization.

639642760 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10861 (or 10857 counting only the distinct ones).

The product of its (nonzero) digits is 326592, while the sum is 43.

The square root of 639642760 is about 25291.1597203450. The cubic root of 639642760 is about 861.6135023677.

The spelling of 639642760 in words is "six hundred thirty-nine million, six hundred forty-two thousand, seven hundred sixty".