639901856564 has 12 divisors (see below), whose sum is σ = 1150093877604. Its totient is φ = 311303605824.

The previous prime is 639901856557. The next prime is 639901856591. The reversal of 639901856564 is 465658109936.

It can be written as a sum of positive squares in 2 ways, for example, as 517162339600 + 122739516964 = 719140^2 + 350342^2 .

It is a junction number, because it is equal to n+sod(n) for n = 639901856497 and 639901856506.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2161830449 + ... + 2161830744.

It is an arithmetic number, because the mean of its divisors is an integer number (95841156467).

Almost surely, 2^639901856564 is an apocalyptic number.

It is an amenable number.

639901856564 is a deficient number, since it is larger than the sum of its proper divisors (510192021040).

639901856564 is a wasteful number, since it uses less digits than its factorization.

639901856564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4323661234 (or 4323661232 counting only the distinct ones).

The product of its (nonzero) digits is 41990400, while the sum is 62.

The spelling of 639901856564 in words is "six hundred thirty-nine billion, nine hundred one million, eight hundred fifty-six thousand, five hundred sixty-four".