639356668 has 12 divisors (see below), whose sum is σ = 1167521040. Its totient is φ = 305779232.

The previous prime is 639356659. The next prime is 639356671. The reversal of 639356668 is 866653936.

It is a congruent number.

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, 3474673 + ... + 3474856.

It is an arithmetic number, because the mean of its divisors is an integer number (97293420).

Almost surely, 2^639356668 is an apocalyptic number.

It is an amenable number.

639356668 is a deficient number, since it is larger than the sum of its proper divisors (528164372).

639356668 is a wasteful number, since it uses less digits than its factorization.

639356668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6949556 (or 6949554 counting only the distinct ones).

The product of its digits is 4199040, while the sum is 52.

The square root of 639356668 is about 25285.5031193765. The cubic root of 639356668 is about 861.4850257110.

The spelling of 639356668 in words is "six hundred thirty-nine million, three hundred fifty-six thousand, six hundred sixty-eight".