639646636 has 6 divisors (see below), whose sum is σ = 1119381620. Its totient is φ = 319823316.

The previous prime is 639646633. The next prime is 639646673. The reversal of 639646636 is 636646936.

It is a super-2 number, since 2×639646636² = 818295637892232992, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 639646636.

It is not an unprimeable number, because it can be changed into a prime (639646633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 79955826 + ... + 79955833.

Almost surely, 2^639646636 is an apocalyptic number.

It is an amenable number.

639646636 is a deficient number, since it is larger than the sum of its proper divisors (479734984).

639646636 is a wasteful number, since it uses less digits than its factorization.

639646636 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 159911663 (or 159911661 counting only the distinct ones).

The product of its digits is 2519424, while the sum is 49.

The square root of 639646636 is about 25291.2363477945. The cubic root of 639646636 is about 861.6152427179.

The spelling of 639646636 in words is "six hundred thirty-nine million, six hundred forty-six thousand, six hundred thirty-six".