638765395984 has 15 divisors (see below), whose sum is σ = 1237614148767. Its totient is φ = 319381099536.

The previous prime is 638765395979. The next prime is 638765395991. The reversal of 638765395984 is 489593567836.

The square root of 638765395984 is 799228.

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

It is a super-2 number, since 2×638765395984² (a number of 24 digits) contains 22 as substring.

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, 3097009 + ... + 3296815.

Almost surely, 2^638765395984 is an apocalyptic number.

638765395984 is the 799228-th square number.

It is an amenable number.

638765395984 is a deficient number, since it is larger than the sum of its proper divisors (598848752783).

638765395984 is an frugal number, since it uses more digits than its factorization.

638765395984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 399622 (or 199809 counting only the distinct ones).

The product of its digits is 1175731200, while the sum is 73.

It can be divided in two parts, 63876 and 5395984, that added together give a triangular number (5459860 = T₃₃₀₄).

The spelling of 638765395984 in words is "six hundred thirty-eight billion, seven hundred sixty-five million, three hundred ninety-five thousand, nine hundred eighty-four".