165811855789 has 2 divisors, whose sum is σ = 165811855790. Its totient is φ = 165811855788.

The previous prime is 165811855757. The next prime is 165811855837. The reversal of 165811855789 is 987558118561.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 119525775625 + 46286080164 = 345725^2 + 215142^2 .

It is a cyclic number.

It is not a de Polignac number, because 165811855789 - 2⁵ = 165811855757 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 165811855789.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (165811855189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82905927894 + 82905927895.

It is an arithmetic number, because the mean of its divisors is an integer number (82905927895).

Almost surely, 2^165811855789 is an apocalyptic number.

It is an amenable number.

165811855789 is a deficient number, since it is larger than the sum of its proper divisors (1).

165811855789 is an equidigital number, since it uses as much as digits as its factorization.

165811855789 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24192000, while the sum is 64.

The spelling of 165811855789 in words is "one hundred sixty-five billion, eight hundred eleven million, eight hundred fifty-five thousand, seven hundred eighty-nine".