165111521 has 2 divisors, whose sum is σ = 165111522. Its totient is φ = 165111520.

The previous prime is 165111481. The next prime is 165111523. The reversal of 165111521 is 125111561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 162435025 + 2676496 = 12745^2 + 1636^2 .

It is a cyclic number.

It is not a de Polignac number, because 165111521 - 2²² = 160917217 is a prime.

Together with 165111523, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (165111523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82555760 + 82555761.

It is an arithmetic number, because the mean of its divisors is an integer number (82555761).

Almost surely, 2^165111521 is an apocalyptic number.

It is an amenable number.

165111521 is a deficient number, since it is larger than the sum of its proper divisors (1).

165111521 is an equidigital number, since it uses as much as digits as its factorization.

165111521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 300, while the sum is 23.

The square root of 165111521 is about 12849.5727944551. The cubic root of 165111521 is about 548.6041973356.

The spelling of 165111521 in words is "one hundred sixty-five million, one hundred eleven thousand, five hundred twenty-one".