638691869124 has 135 divisors (see below), whose sum is σ = 1730356969341. Its totient is φ = 205421741280.

The previous prime is 638691869119. The next prime is 638691869131. The reversal of 638691869124 is 421968196836.

The square root of 638691869124 is 799182.

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

638691869124 is a `hidden beast` number, since 6 + 386 + 91 + 86 + 91 + 2 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 334914523524 + 303777345600 = 578718^2 + 551160^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 417172239 + ... + 417173769.

Almost surely, 2^638691869124 is an apocalyptic number.

638691869124 is the 799182-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 638691869124

638691869124 is an abundant number, since it is smaller than the sum of its proper divisors (1091665100217).

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

638691869124 is an equidigital number, since it uses as much as digits as its factorization.

638691869124 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3136 (or 1565 counting only the distinct ones).

The product of its digits is 26873856, while the sum is 63.

The spelling of 638691869124 in words is "six hundred thirty-eight billion, six hundred ninety-one million, eight hundred sixty-nine thousand, one hundred twenty-four".