165989 has 4 divisors (see below), whose sum is σ = 167424. Its totient is φ = 164556.

The previous prime is 165983. The next prime is 166013. The reversal of 165989 is 989561.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-165989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (165983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 527 + ... + 780.

It is an arithmetic number, because the mean of its divisors is an integer number (41856).

2¹⁶⁵⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

165989 is a deficient number, since it is larger than the sum of its proper divisors (1435).

165989 is a wasteful number, since it uses less digits than its factorization.

165989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1434.

The product of its digits is 19440, while the sum is 38.

The square root of 165989 is about 407.4174763066. The cubic root of 165989 is about 54.9574326281.

The spelling of 165989 in words is "one hundred sixty-five thousand, nine hundred eighty-nine".