668817564538 has 8 divisors (see below), whose sum is σ = 1003584522420. Its totient is φ = 334289390400.

The previous prime is 668817564533. The next prime is 668817564587. The reversal of 668817564538 is 835465718866.

668817564538 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 638380226169 + 30437338369 = 798987^2 + 174463^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (668817564533) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 59688933 + ... + 59700136.

Almost surely, 2^668817564538 is an apocalyptic number.

668817564538 is a deficient number, since it is larger than the sum of its proper divisors (334766957882).

668817564538 is a wasteful number, since it uses less digits than its factorization.

668817564538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 119391872.

The product of its digits is 232243200, while the sum is 67.

The spelling of 668817564538 in words is "six hundred sixty-eight billion, eight hundred seventeen million, five hundred sixty-four thousand, five hundred thirty-eight".