639568 has 20 divisors (see below), whose sum is σ = 1258848. Its totient is φ = 314720.

The previous prime is 639563. The next prime is 639571. The reversal of 639568 is 865936.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639563) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 855 + ... + 1417.

2⁶³⁹⁵⁶⁸ is an apocalyptic number.

It is an amenable number.

639568 is a deficient number, since it is larger than the sum of its proper divisors (619280).

639568 is a wasteful number, since it uses less digits than its factorization.

639568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 642 (or 636 counting only the distinct ones).

The product of its digits is 38880, while the sum is 37.

The square root of 639568 is about 799.7299544221. The cubic root of 639568 is about 86.1579933247.

The spelling of 639568 in words is "six hundred thirty-nine thousand, five hundred sixty-eight".