165662661 has 4 divisors (see below), whose sum is σ = 220883552. Its totient is φ = 110441772.

The previous prime is 165662621. The next prime is 165662663. The reversal of 165662661 is 166266561.

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: 166266561 = 3 ⋅55422187.

It is not a de Polignac number, because 165662661 - 2⁶ = 165662597 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 (165662663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 27610441 + ... + 27610446.

It is an arithmetic number, because the mean of its divisors is an integer number (55220888).

Almost surely, 2^165662661 is an apocalyptic number.

It is an amenable number.

165662661 is a deficient number, since it is larger than the sum of its proper divisors (55220891).

165662661 is an equidigital number, since it uses as much as digits as its factorization.

165662661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55220890.

The product of its digits is 77760, while the sum is 39.

The square root of 165662661 is about 12871.0007769404. Note that the first 3 decimals coincide. The cubic root of 165662661 is about 549.2139305147.

The spelling of 165662661 in words is "one hundred sixty-five million, six hundred sixty-two thousand, six hundred sixty-one".