161510665 has 4 divisors (see below), whose sum is σ = 193812804. Its totient is φ = 129208528.

The previous prime is 161510653. The next prime is 161510689. The reversal of 161510665 is 566015161.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 566015161 = 14107 ⋅40123.

It can be written as a sum of positive squares in 2 ways, for example, as 66194496 + 95316169 = 8136^2 + 9763^2 .

It is a cyclic number.

It is not a de Polignac number, because 161510665 - 2²⁵ = 127956233 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16151062 + ... + 16151071.

It is an arithmetic number, because the mean of its divisors is an integer number (48453201).

Almost surely, 2^161510665 is an apocalyptic number.

It is an amenable number.

161510665 is a deficient number, since it is larger than the sum of its proper divisors (32302139).

161510665 is an equidigital number, since it uses as much as digits as its factorization.

161510665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32302138.

The product of its (nonzero) digits is 5400, while the sum is 31.

The square root of 161510665 is about 12708.6846290244. The cubic root of 161510665 is about 544.5867472984.

The spelling of 161510665 in words is "one hundred sixty-one million, five hundred ten thousand, six hundred sixty-five".