666116605566 has 24 divisors (see below), whose sum is σ = 1519213311720. Its totient is φ = 210352612176.

The previous prime is 666116605543. The next prime is 666116605579. The reversal of 666116605566 is 665506611666.

It is a super-2 number, since 2×666116605566² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 973854345 + ... + 973855028.

It is an arithmetic number, because the mean of its divisors is an integer number (63300554655).

Almost surely, 2^666116605566 is an apocalyptic number.

666116605566 is an abundant number, since it is smaller than the sum of its proper divisors (853096706154).

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

666116605566 is a wasteful number, since it uses less digits than its factorization.

666116605566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1947709400 (or 1947709397 counting only the distinct ones).

The product of its (nonzero) digits is 6998400, while the sum is 54.

The spelling of 666116605566 in words is "six hundred sixty-six billion, one hundred sixteen million, six hundred five thousand, five hundred sixty-six".