205989 has 16 divisors (see below), whose sum is σ = 332928. Its totient is φ = 110592.

The previous prime is 205981. The next prime is 205991. The reversal of 205989 is 989502.

It is not a de Polignac number, because 205989 - 2³ = 205981 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205981) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 69 + ... + 645.

It is an arithmetic number, because the mean of its divisors is an integer number (20808).

2²⁰⁵⁹⁸⁹ is an apocalyptic number.

It is an amenable number.

205989 is a deficient number, since it is larger than the sum of its proper divisors (126939).

205989 is a wasteful number, since it uses less digits than its factorization.

205989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 604.

The product of its (nonzero) digits is 6480, while the sum is 33.

The square root of 205989 is about 453.8601106068. The cubic root of 205989 is about 59.0583545983.

The spelling of 205989 in words is "two hundred five thousand, nine hundred eighty-nine".