165611661 has 8 divisors (see below), whose sum is σ = 230416320. Its totient is φ = 105607392.

The previous prime is 165611659. The next prime is 165611681. The reversal of 165611661 is 166116561.

165611661 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 165611661 - 2¹ = 165611659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165611681) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1200016 + ... + 1200153.

It is an arithmetic number, because the mean of its divisors is an integer number (28802040).

Almost surely, 2^165611661 is an apocalyptic number.

It is an amenable number.

165611661 is a deficient number, since it is larger than the sum of its proper divisors (64804659).

165611661 is a wasteful number, since it uses less digits than its factorization.

165611661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2400195.

The product of its digits is 6480, while the sum is 33.

The square root of 165611661 is about 12869.0194265142. The cubic root of 165611661 is about 549.1575653988.

The spelling of 165611661 in words is "one hundred sixty-five million, six hundred eleven thousand, six hundred sixty-one".