165808561 has 2 divisors, whose sum is σ = 165808562. Its totient is φ = 165808560.

The previous prime is 165808543. The next prime is 165808579.

165808561 is nontrivially palindromic in base 10.

It is a balanced prime because it is at equal distance from previous prime (165808543) and next prime (165808579).

It can be written as a sum of positive squares in only one way, i.e., 152992161 + 12816400 = 12369^2 + 3580^2 .

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 165808561 - 2⁵ = 165808529 is a prime.

It is not a weakly prime, because it can be changed into another prime (165808861) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82904280 + 82904281.

It is an arithmetic number, because the mean of its divisors is an integer number (82904281).

Almost surely, 2^165808561 is an apocalyptic number.

It is an amenable number.

165808561 is a deficient number, since it is larger than the sum of its proper divisors (1).

165808561 is an equidigital number, since it uses as much as digits as its factorization.

165808561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 57600, while the sum is 40.

The square root of 165808561 is about 12876.6673095176. The cubic root of 165808561 is about 549.3751150966.

The spelling of 165808561 in words is "one hundred sixty-five million, eight hundred eight thousand, five hundred sixty-one".