639644562840 has 256 divisors, whose sum is σ = 1980130406400. Its totient is φ = 165232742400.

The previous prime is 639644562839. The next prime is 639644562853. The reversal of 639644562840 is 48265446936.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 176549269 + ... + 176552891.

It is an arithmetic number, because the mean of its divisors is an integer number (7734884400).

Almost surely, 2^639644562840 is an apocalyptic number.

639644562840 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639644562840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (990065203200).

639644562840 is an abundant number, since it is smaller than the sum of its proper divisors (1340485843560).

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

639644562840 is a wasteful number, since it uses less digits than its factorization.

639644562840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4058 (or 4054 counting only the distinct ones).

The product of its (nonzero) digits is 29859840, while the sum is 57.

The spelling of 639644562840 in words is "six hundred thirty-nine billion, six hundred forty-four million, five hundred sixty-two thousand, eight hundred forty".