165121979 has 4 divisors (see below), whose sum is σ = 180133080. Its totient is φ = 150110880.

The previous prime is 165121961. The next prime is 165121981. The reversal of 165121979 is 979121561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 979121561 = 11 ⋅89011051.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165121979 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165121909) 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, 7505534 + ... + 7505555.

It is an arithmetic number, because the mean of its divisors is an integer number (45033270).

Almost surely, 2^165121979 is an apocalyptic number.

165121979 is a deficient number, since it is larger than the sum of its proper divisors (15011101).

165121979 is a wasteful number, since it uses less digits than its factorization.

165121979 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15011100.

The product of its digits is 34020, while the sum is 41.

The square root of 165121979 is about 12849.9797276105. The cubic root of 165121979 is about 548.6157797730.

The spelling of 165121979 in words is "one hundred sixty-five million, one hundred twenty-one thousand, nine hundred seventy-nine".