165987817 has 2 divisors, whose sum is σ = 165987818. Its totient is φ = 165987816.

The previous prime is 165987763. The next prime is 165987821. The reversal of 165987817 is 718789561.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 113294736 + 52693081 = 10644^2 + 7259^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165987817 is a prime.

It is not a weakly prime, because it can be changed into another prime (165987517) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82993908 + 82993909.

It is an arithmetic number, because the mean of its divisors is an integer number (82993909).

Almost surely, 2^165987817 is an apocalyptic number.

It is an amenable number.

165987817 is a deficient number, since it is larger than the sum of its proper divisors (1).

165987817 is an equidigital number, since it uses as much as digits as its factorization.

165987817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 846720, while the sum is 52.

The square root of 165987817 is about 12883.6259259573. The cubic root of 165987817 is about 549.5730206767.

The spelling of 165987817 in words is "one hundred sixty-five million, nine hundred eighty-seven thousand, eight hundred seventeen".