165515161 has 4 divisors (see below), whose sum is σ = 189160192. Its totient is φ = 141870132.

The previous prime is 165515159. The next prime is 165515167. The reversal of 165515161 is 161515561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 161515561 = 19 ⋅8500819.

It is a cyclic number.

It is not a de Polignac number, because 165515161 - 2¹ = 165515159 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165515167) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11822505 + ... + 11822518.

It is an arithmetic number, because the mean of its divisors is an integer number (47290048).

Almost surely, 2^165515161 is an apocalyptic number.

It is an amenable number.

165515161 is a deficient number, since it is larger than the sum of its proper divisors (23645031).

165515161 is an equidigital number, since it uses as much as digits as its factorization.

165515161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23645030.

The product of its digits is 4500, while the sum is 31.

The square root of 165515161 is about 12865.2695657728. The cubic root of 165515161 is about 549.0508820871.

It can be divided in two parts, 16551 and 5161, that added together give a palindrome (21712).

The spelling of 165515161 in words is "one hundred sixty-five million, five hundred fifteen thousand, one hundred sixty-one".