205815 has 8 divisors (see below), whose sum is σ = 329328. Its totient is φ = 109760.

The previous prime is 205783. The next prime is 205817. The reversal of 205815 is 518502.

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

It is not a de Polignac number, because 205815 - 2⁵ = 205783 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 205791 and 205800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205817) 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, 6846 + ... + 6875.

It is an arithmetic number, because the mean of its divisors is an integer number (41166).

2²⁰⁵⁸¹⁵ is an apocalyptic number.

205815 is a deficient number, since it is larger than the sum of its proper divisors (123513).

205815 is a wasteful number, since it uses less digits than its factorization.

205815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13729.

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 205815 is about 453.6683810891. The cubic root of 205815 is about 59.0417209456.

The spelling of 205815 in words is "two hundred five thousand, eight hundred fifteen".