639656 has 16 divisors (see below), whose sum is σ = 1232340. Its totient is φ = 311040.

The previous prime is 639647. The next prime is 639671. The reversal of 639656 is 656936.

It can be written as a sum of positive squares in 2 ways, for example, as 586756 + 52900 = 766^2 + 230^2 .

It is an unprimeable number.

639656 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 785 + ... + 1376.

2⁶³⁹⁶⁵⁶ is an apocalyptic number.

It is an amenable number.

639656 is a deficient number, since it is larger than the sum of its proper divisors (592684).

639656 is a wasteful number, since it uses less digits than its factorization.

639656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2204 (or 2200 counting only the distinct ones).

The product of its digits is 29160, while the sum is 35.

The square root of 639656 is about 799.7849711016. The cubic root of 639656 is about 86.1619447188.

The spelling of 639656 in words is "six hundred thirty-nine thousand, six hundred fifty-six".