165231661 has 4 divisors (see below), whose sum is σ = 188836192. Its totient is φ = 141627132.

The previous prime is 165231659. The next prime is 165231709. The reversal of 165231661 is 166132561.

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.

It is a cyclic number.

It is not a de Polignac number, because 165231661 - 2¹ = 165231659 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165231611) 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, 11802255 + ... + 11802268.

It is an arithmetic number, because the mean of its divisors is an integer number (47209048).

Almost surely, 2^165231661 is an apocalyptic number.

It is an amenable number.

165231661 is a deficient number, since it is larger than the sum of its proper divisors (23604531).

165231661 is an equidigital number, since it uses as much as digits as its factorization.

165231661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23604530.

The product of its digits is 6480, while the sum is 31.

The square root of 165231661 is about 12854.2468079620. The cubic root of 165231661 is about 548.7372252601.

The spelling of 165231661 in words is "one hundred sixty-five million, two hundred thirty-one thousand, six hundred sixty-one".