165561089 has 2 divisors, whose sum is σ = 165561090. Its totient is φ = 165561088.

The previous prime is 165561043. The next prime is 165561091. The reversal of 165561089 is 980165561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 142444225 + 23116864 = 11935^2 + 4808^2 .

It is a cyclic number.

It is not a de Polignac number, because 165561089 - 2⁸ = 165560833 is a prime.

It is a Sophie Germain prime.

Together with 165561091, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (165561289) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82780544 + 82780545.

It is an arithmetic number, because the mean of its divisors is an integer number (82780545).

Almost surely, 2^165561089 is an apocalyptic number.

It is an amenable number.

165561089 is a deficient number, since it is larger than the sum of its proper divisors (1).

165561089 is an equidigital number, since it uses as much as digits as its factorization.

165561089 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64800, while the sum is 41.

The square root of 165561089 is about 12867.0544026207. The cubic root of 165561089 is about 549.1016618801.

The spelling of 165561089 in words is "one hundred sixty-five million, five hundred sixty-one thousand, eighty-nine".