205639 has 8 divisors (see below), whose sum is σ = 243360. Its totient is φ = 170016.

The previous prime is 205633. The next prime is 205651. The reversal of 205639 is 936502.

205639 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 205639 - 2⁵ = 205607 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 (205633) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 304 + ... + 709.

It is an arithmetic number, because the mean of its divisors is an integer number (30420).

205639 is a Friedman number, since it can be written as 260+59^3, using all its digits and the basic arithmetic operations.

2²⁰⁵⁶³⁹ is an apocalyptic number.

205639 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

205639 is a deficient number, since it is larger than the sum of its proper divisors (37721).

205639 is a wasteful number, since it uses less digits than its factorization.

205639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1049.

The product of its (nonzero) digits is 1620, while the sum is 25.

The square root of 205639 is about 453.4743653174. The cubic root of 205639 is about 59.0248865615.

The spelling of 205639 in words is "two hundred five thousand, six hundred thirty-nine".