639563956 has 6 divisors (see below), whose sum is σ = 1119236930. Its totient is φ = 319781976.

The previous prime is 639563933. The next prime is 639563963. The reversal of 639563956 is 659365936.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 517107600 + 122456356 = 22740^2 + 11066^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 79945491 + ... + 79945498.

Almost surely, 2^639563956 is an apocalyptic number.

It is an amenable number.

639563956 is a deficient number, since it is larger than the sum of its proper divisors (479672974).

639563956 is a wasteful number, since it uses less digits than its factorization.

639563956 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159890993 (or 159890991 counting only the distinct ones).

The product of its digits is 3936600, while the sum is 52.

The square root of 639563956 is about 25289.6017366822. The cubic root of 639563956 is about 861.5781173147.

The spelling of 639563956 in words is "six hundred thirty-nine million, five hundred sixty-three thousand, nine hundred fifty-six".