165817181 has 2 divisors, whose sum is σ = 165817182. Its totient is φ = 165817180.

The previous prime is 165817153. The next prime is 165817193. The reversal of 165817181 is 181718561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 146192281 + 19624900 = 12091^2 + 4430^2 .

It is a cyclic number.

It is not a de Polignac number, because 165817181 - 2⁶ = 165817117 is a prime.

It is a super-2 number, since 2×165817181² = 54990675029573522, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165817111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82908590 + 82908591.

It is an arithmetic number, because the mean of its divisors is an integer number (82908591).

Almost surely, 2^165817181 is an apocalyptic number.

It is an amenable number.

165817181 is a deficient number, since it is larger than the sum of its proper divisors (1).

165817181 is an equidigital number, since it uses as much as digits as its factorization.

165817181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13440, while the sum is 38.

The square root of 165817181 is about 12877.0020191037. The cubic root of 165817181 is about 549.3846351748.

The spelling of 165817181 in words is "one hundred sixty-five million, eight hundred seventeen thousand, one hundred eighty-one".