638213655168 has 80 divisors (see below), whose sum is σ = 1899313527210. Its totient is φ = 212737881600.

The previous prime is 638213655143. The next prime is 638213655169. The reversal of 638213655168 is 861556312836.

It is a happy number.

638213655168 is a `hidden beast` number, since 6 + 3 + 8 + 21 + 3 + 6 + 551 + 68 = 666.

It can be written as a sum of positive squares in only one way, i.e., 504906882624 + 133306772544 = 710568^2 + 365112^2 .

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (638213655169) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 30767683 + ... + 30788418.

Almost surely, 2^638213655168 is an apocalyptic number.

It is an amenable number.

638213655168 is an abundant number, since it is smaller than the sum of its proper divisors (1261099872042).

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

638213655168 is an equidigital number, since it uses as much as digits as its factorization.

638213655168 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61556127 (or 61556106 counting only the distinct ones).

The product of its digits is 6220800, while the sum is 54.

The spelling of 638213655168 in words is "six hundred thirty-eight billion, two hundred thirteen million, six hundred fifty-five thousand, one hundred sixty-eight".