638563332881 has 16 divisors (see below), whose sum is σ = 691907920704. Its totient is φ = 586974657024.

The previous prime is 638563332857. The next prime is 638563332923. The reversal of 638563332881 is 188233365836.

It is a cyclic number.

It is not a de Polignac number, because 638563332881 - 2¹⁴ = 638563316497 is a prime.

It is a super-2 number, since 2×638563332881² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638563332811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10879445 + ... + 10937981.

It is an arithmetic number, because the mean of its divisors is an integer number (43244245044).

Almost surely, 2^638563332881 is an apocalyptic number.

It is an amenable number.

638563332881 is a deficient number, since it is larger than the sum of its proper divisors (53344587823).

638563332881 is a wasteful number, since it uses less digits than its factorization.

638563332881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73520.

The product of its digits is 14929920, while the sum is 56.

The spelling of 638563332881 in words is "six hundred thirty-eight billion, five hundred sixty-three million, three hundred thirty-two thousand, eight hundred eighty-one".