165881081 has 2 divisors, whose sum is σ = 165881082. Its totient is φ = 165881080.

The previous prime is 165881047. The next prime is 165881117. The reversal of 165881081 is 180188561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 86955625 + 78925456 = 9325^2 + 8884^2 .

It is a cyclic number.

It is not a de Polignac number, because 165881081 - 2²⁶ = 98772217 is a prime.

It is a super-2 number, since 2×165881081² = 55033066067457122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (165881011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82940540 + 82940541.

It is an arithmetic number, because the mean of its divisors is an integer number (82940541).

Almost surely, 2^165881081 is an apocalyptic number.

It is an amenable number.

165881081 is a deficient number, since it is larger than the sum of its proper divisors (1).

165881081 is an equidigital number, since it uses as much as digits as its factorization.

165881081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15360, while the sum is 38.

The square root of 165881081 is about 12879.4829476963. The cubic root of 165881081 is about 549.4551971625.

The spelling of 165881081 in words is "one hundred sixty-five million, eight hundred eighty-one thousand, eighty-one".