639895668 has 24 divisors (see below), whose sum is σ = 1494927168. Its totient is φ = 213036096.

The previous prime is 639895667. The next prime is 639895679. The reversal of 639895668 is 866598936.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639895667) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22521 + ... + 42272.

It is an arithmetic number, because the mean of its divisors is an integer number (62288632).

Almost surely, 2^639895668 is an apocalyptic number.

It is an amenable number.

639895668 is an abundant number, since it is smaller than the sum of its proper divisors (855031500).

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

639895668 is a wasteful number, since it uses less digits than its factorization.

639895668 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65623 (or 65621 counting only the distinct ones).

The product of its digits is 16796160, while the sum is 60.

The square root of 639895668 is about 25296.1591550970. The cubic root of 639895668 is about 861.7270450345.

The spelling of 639895668 in words is "six hundred thirty-nine million, eight hundred ninety-five thousand, six hundred sixty-eight".