639769620736 has 27 divisors (see below), whose sum is σ = 1277065687303. Its totient is φ = 319878411520.

The previous prime is 639769620713. The next prime is 639769620767. The reversal of 639769620736 is 637026967936.

The square root of 639769620736 is 799856.

It is a perfect power (a square), and thus also a powerful number.

It is a Harshad number since it is a multiple of its sum of digits (64).

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 12772701 + ... + 12822691.

Almost surely, 2^639769620736 is an apocalyptic number.

639769620736 is the 799856-th square number.

It is an amenable number.

639769620736 is a deficient number, since it is larger than the sum of its proper divisors (637296066567).

639769620736 is an frugal number, since it uses more digits than its factorization.

639769620736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 99998 (or 49993 counting only the distinct ones).

The product of its (nonzero) digits is 92588832, while the sum is 64.

Multiplying 639769620736 by its sum of digits (64), we get a square (40945255727104 = 6398848²).

639769620736 divided by its sum of digits (64) gives a square (9996400324 = 99982²).

The spelling of 639769620736 in words is "six hundred thirty-nine billion, seven hundred sixty-nine million, six hundred twenty thousand, seven hundred thirty-six".