165859 has 4 divisors (see below), whose sum is σ = 168640. Its totient is φ = 163080.

The previous prime is 165857. The next prime is 165877. The reversal of 165859 is 958561.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 958561 = 877 ⋅1093.

It is a cyclic number.

It is not a de Polignac number, because 165859 - 2¹ = 165857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (165857) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1299 + ... + 1420.

It is an arithmetic number, because the mean of its divisors is an integer number (42160).

2¹⁶⁵⁸⁵⁹ is an apocalyptic number.

165859 is a deficient number, since it is larger than the sum of its proper divisors (2781).

165859 is an equidigital number, since it uses as much as digits as its factorization.

165859 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2780.

The product of its digits is 10800, while the sum is 34.

The square root of 165859 is about 407.2579035452. The cubic root of 165859 is about 54.9430816125.

It can be divided in two parts, 165 and 859, that added together give a 10-th power (1024 = 2¹⁰).

The spelling of 165859 in words is "one hundred sixty-five thousand, eight hundred fifty-nine".