165640091 has 2 divisors, whose sum is σ = 165640092. Its totient is φ = 165640090.

The previous prime is 165640063. The next prime is 165640117. The reversal of 165640091 is 190046561.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 165640091 - 2²⁶ = 98531227 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (165640001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82820045 + 82820046.

It is an arithmetic number, because the mean of its divisors is an integer number (82820046).

Almost surely, 2^165640091 is an apocalyptic number.

165640091 is a deficient number, since it is larger than the sum of its proper divisors (1).

165640091 is an equidigital number, since it uses as much as digits as its factorization.

165640091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6480, while the sum is 32.

The square root of 165640091 is about 12870.1239698769. The cubic root of 165640091 is about 549.1889876150.

The spelling of 165640091 in words is "one hundred sixty-five million, six hundred forty thousand, ninety-one".