639561728620 has 24 divisors (see below), whose sum is σ = 1350038600064. Its totient is φ = 254499173376.

The previous prime is 639561728569. The next prime is 639561728653. The reversal of 639561728620 is 26827165936.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 82840924 + ... + 82848643.

It is an arithmetic number, because the mean of its divisors is an integer number (56251608336).

Almost surely, 2^639561728620 is an apocalyptic number.

It is an amenable number.

639561728620 is an abundant number, since it is smaller than the sum of its proper divisors (710476871444).

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

639561728620 is a wasteful number, since it uses less digits than its factorization.

639561728620 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 165689769 (or 165689767 counting only the distinct ones).

The product of its (nonzero) digits is 6531840, while the sum is 55.

The spelling of 639561728620 in words is "six hundred thirty-nine billion, five hundred sixty-one million, seven hundred twenty-eight thousand, six hundred twenty".