165891 has 12 divisors (see below), whose sum is σ = 243656. Its totient is φ = 100320.

The previous prime is 165887. The next prime is 165901. The reversal of 165891 is 198561.

It is a happy number.

165891 is digitally balanced in base 7, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 165891 - 2² = 165887 is a prime.

It is a Duffinian number.

165891 is a modest number, since divided by 891 gives 165 as remainder.

165891 is strictly pandigital in base 7.

It is not an unprimeable number, because it can be changed into a prime (165811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 135 + ... + 591.

2¹⁶⁵⁸⁹¹ is an apocalyptic number.

165891 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

165891 is a deficient number, since it is larger than the sum of its proper divisors (77765).

165891 is a wasteful number, since it uses less digits than its factorization.

165891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 482 (or 471 counting only the distinct ones).

The product of its digits is 2160, while the sum is 30.

The square root of 165891 is about 407.2971887946. The cubic root of 165891 is about 54.9466148657.

The spelling of 165891 in words is "one hundred sixty-five thousand, eight hundred ninety-one".