165755324921 has 2 divisors, whose sum is σ = 165755324922. Its totient is φ = 165755324920.

The previous prime is 165755324899. The next prime is 165755324947. The reversal of 165755324921 is 129423557561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 119028450025 + 46726874896 = 345005^2 + 216164^2 .

It is an emirp because it is prime and its reverse (129423557561) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 165755324921 - 2⁶ = 165755324857 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 165755324921.

It is not a weakly prime, because it can be changed into another prime (165755324321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82877662460 + 82877662461.

It is an arithmetic number, because the mean of its divisors is an integer number (82877662461).

Almost surely, 2^165755324921 is an apocalyptic number.

It is an amenable number.

165755324921 is a deficient number, since it is larger than the sum of its proper divisors (1).

165755324921 is an equidigital number, since it uses as much as digits as its factorization.

165755324921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2268000, while the sum is 50.

The spelling of 165755324921 in words is "one hundred sixty-five billion, seven hundred fifty-five million, three hundred twenty-four thousand, nine hundred twenty-one".