165910661 has 16 divisors (see below), whose sum is σ = 198451200. Its totient is φ = 135617328.

The previous prime is 165910631. The next prime is 165910681. The reversal of 165910661 is 166019561.

It is not a de Polignac number, because 165910661 - 2¹⁰ = 165909637 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 (165910631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 59660 + ... + 62378.

It is an arithmetic number, because the mean of its divisors is an integer number (12403200).

Almost surely, 2^165910661 is an apocalyptic number.

It is an amenable number.

165910661 is a deficient number, since it is larger than the sum of its proper divisors (32540539).

165910661 is a wasteful number, since it uses less digits than its factorization.

165910661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3128.

The product of its (nonzero) digits is 9720, while the sum is 35.

The square root of 165910661 is about 12880.6312345319. The cubic root of 165910661 is about 549.4878549329.

Subtracting 165910661 from its reverse (166019561), we obtain a square (108900 = 330²).

The spelling of 165910661 in words is "one hundred sixty-five million, nine hundred ten thousand, six hundred sixty-one".