165544445561 has 16 divisors (see below), whose sum is σ = 185600880960. Its totient is φ = 146353072320.

The previous prime is 165544445531. The next prime is 165544445567.

165544445561 is nontrivially palindromic in base 10.

It is a cyclic number.

It is not a de Polignac number, because 165544445561 - 2⁶ = 165544445497 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (165544445567) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 655850 + ... + 872483.

It is an arithmetic number, because the mean of its divisors is an integer number (11600055060).

Almost surely, 2^165544445561 is an apocalyptic number.

165544445561 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

165544445561 is a deficient number, since it is larger than the sum of its proper divisors (20056435399).

165544445561 is a wasteful number, since it uses less digits than its factorization.

165544445561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1528616.

The product of its digits is 5760000, while the sum is 50.

The spelling of 165544445561 in words is "one hundred sixty-five billion, five hundred forty-four million, four hundred forty-five thousand, five hundred sixty-one".