639403640 has 16 divisors (see below), whose sum is σ = 1438658280. Its totient is φ = 255761440.

The previous prime is 639403621. The next prime is 639403673. The reversal of 639403640 is 46304936.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 639403640.

It is a congruent number.

It is an unprimeable number.

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 in 3 ways as a sum of consecutive naturals, for example, 7992506 + ... + 7992585.

Almost surely, 2^639403640 is an apocalyptic number.

It is an amenable number.

639403640 is an abundant number, since it is smaller than the sum of its proper divisors (799254640).

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

639403640 is a wasteful number, since it uses less digits than its factorization.

639403640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15985102 (or 15985098 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 35.

The square root of 639403640 is about 25286.4319349330. The cubic root of 639403640 is about 861.5061222735.

The spelling of 639403640 in words is "six hundred thirty-nine million, four hundred three thousand, six hundred forty".