165636661 has 16 divisors (see below), whose sum is σ = 190987200. Its totient is φ = 142587648.

The previous prime is 165636641. The next prime is 165636673. The reversal of 165636661 is 166636561.

It is a cyclic number.

It is not a de Polignac number, because 165636661 - 2⁵ = 165636629 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 (165636641) 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 15 ways as a sum of consecutive naturals, for example, 526 + ... + 18208.

It is an arithmetic number, because the mean of its divisors is an integer number (11936700).

Almost surely, 2^165636661 is an apocalyptic number.

It is an amenable number.

165636661 is a deficient number, since it is larger than the sum of its proper divisors (25350539).

165636661 is a wasteful number, since it uses less digits than its factorization.

165636661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17748.

The product of its digits is 116640, while the sum is 40.

The square root of 165636661 is about 12869.9907148374. The cubic root of 165636661 is about 549.1851968032.

The spelling of 165636661 in words is "one hundred sixty-five million, six hundred thirty-six thousand, six hundred sixty-one".