166165101561561 has 32 divisors (see below), whose sum is σ = 227795695919616. Its totient is φ = 107662325472000.

The previous prime is 166165101561517. The next prime is 166165101561577. The reversal of 166165101561561 is 165165101561661.

It is not a de Polignac number, because 166165101561561 - 2³⁰ = 166164027819737 is a prime.

It is a super-2 number, since 2×166165101561561² (a number of 29 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (166165101561581) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 2713710816 + ... + 2713772046.

It is an arithmetic number, because the mean of its divisors is an integer number (7118615497488).

Almost surely, 2^{166165101561561} is an apocalyptic number.

It is an amenable number.

166165101561561 is a deficient number, since it is larger than the sum of its proper divisors (61630594358055).

166165101561561 is a wasteful number, since it uses less digits than its factorization.

166165101561561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88193.

The product of its (nonzero) digits is 972000, while the sum is 51.

The spelling of 166165101561561 in words is "one hundred sixty-six trillion, one hundred sixty-five billion, one hundred one million, five hundred sixty-one thousand, five hundred sixty-one".