165109891 has 2 divisors, whose sum is σ = 165109892. Its totient is φ = 165109890.

The previous prime is 165109853. The next prime is 165109913. The reversal of 165109891 is 198901561.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 165109891 - 2¹¹ = 165107843 is a prime.

It is a super-2 number, since 2×165109891² = 54522552212063762, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (165109291) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82554945 + 82554946.

It is an arithmetic number, because the mean of its divisors is an integer number (82554946).

Almost surely, 2^165109891 is an apocalyptic number.

165109891 is a deficient number, since it is larger than the sum of its proper divisors (1).

165109891 is an equidigital number, since it uses as much as digits as its factorization.

165109891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 19440, while the sum is 40.

The square root of 165109891 is about 12849.5093680654. The cubic root of 165109891 is about 548.6023920350.

The spelling of 165109891 in words is "one hundred sixty-five million, one hundred nine thousand, eight hundred ninety-one".