639650668 has 12 divisors (see below), whose sum is σ = 1119565720. Its totient is φ = 319774752.

The previous prime is 639650663. The next prime is 639650699. The reversal of 639650668 is 866056936.

It is not an unprimeable number, because it can be changed into a prime (639650663) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 43843 + ... + 56581.

Almost surely, 2^639650668 is an apocalyptic number.

It is an amenable number.

639650668 is a deficient number, since it is larger than the sum of its proper divisors (479915052).

639650668 is a wasteful number, since it uses less digits than its factorization.

639650668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25296 (or 25294 counting only the distinct ones).

The product of its (nonzero) digits is 1399680, while the sum is 49.

The square root of 639650668 is about 25291.3160590745. The cubic root of 639650668 is about 861.6170531057.

The spelling of 639650668 in words is "six hundred thirty-nine million, six hundred fifty thousand, six hundred sixty-eight".