165155555161 has 4 divisors (see below), whose sum is σ = 169619218852. Its totient is φ = 160691891472.

The previous prime is 165155555129. The next prime is 165155555167. The reversal of 165155555161 is 161555551561.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 161555551561 = 1559 ⋅103627679.

It can be written as a sum of positive squares in 2 ways, for example, as 140958197136 + 24197358025 = 375444^2 + 155555^2 .

It is a cyclic number.

It is not a de Polignac number, because 165155555161 - 2⁵ = 165155555129 is a prime.

It is a super-2 number, since 2×165155555161² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165155555167) 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, 2231831790 + ... + 2231831863.

It is an arithmetic number, because the mean of its divisors is an integer number (42404804713).

Almost surely, 2^165155555161 is an apocalyptic number.

It is an amenable number.

165155555161 is a deficient number, since it is larger than the sum of its proper divisors (4463663691).

165155555161 is an equidigital number, since it uses as much as digits as its factorization.

165155555161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4463663690.

The product of its digits is 562500, while the sum is 46.

The spelling of 165155555161 in words is "one hundred sixty-five billion, one hundred fifty-five million, five hundred fifty-five thousand, one hundred sixty-one".