165940660561 has 8 divisors (see below), whose sum is σ = 180858404160. Its totient is φ = 151330499472.

The previous prime is 165940660541. The next prime is 165940660579. The reversal of 165940660561 is 165066049561.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165940660561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165940660531) 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 7 ways as a sum of consecutive naturals, for example, 76894501 + ... + 76896658.

It is an arithmetic number, because the mean of its divisors is an integer number (22607300520).

Almost surely, 2^165940660561 is an apocalyptic number.

It is an amenable number.

165940660561 is a deficient number, since it is larger than the sum of its proper divisors (14917743599).

165940660561 is a wasteful number, since it uses less digits than its factorization.

165940660561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153791255.

The product of its (nonzero) digits is 1166400, while the sum is 49.

The spelling of 165940660561 in words is "one hundred sixty-five billion, nine hundred forty million, six hundred sixty thousand, five hundred sixty-one".