66561116556 has 48 divisors (see below), whose sum is σ = 171105838848. Its totient is φ = 19970328000.

The previous prime is 66561116539. The next prime is 66561116579. The reversal of 66561116556 is 65561116566.

It is a super-2 number, since 2×66561116556² (a number of 22 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2482960 + ... + 2509623.

It is an arithmetic number, because the mean of its divisors is an integer number (3564704976).

Almost surely, 2^66561116556 is an apocalyptic number.

66561116556 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is an amenable number.

66561116556 is an abundant number, since it is smaller than the sum of its proper divisors (104544722292).

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

66561116556 is a wasteful number, since it uses less digits than its factorization.

66561116556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4992702 (or 4992700 counting only the distinct ones).

The product of its digits is 972000, while the sum is 48.

The spelling of 66561116556 in words is "sixty-six billion, five hundred sixty-one million, one hundred sixteen thousand, five hundred fifty-six".