285205 has 4 divisors (see below), whose sum is σ = 342252. Its totient is φ = 228160.

The previous prime is 285199. The next prime is 285221. The reversal of 285205 is 502582.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 502582 = 2 ⋅251291.

It can be written as a sum of positive squares in 2 ways, for example, as 106276 + 178929 = 326^2 + 423^2 .

It is a de Polignac number, because none of the positive numbers 2^k-285205 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an Ulam number.

It is a Duffinian number.

285205 is a lucky number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28516 + ... + 28525.

It is an arithmetic number, because the mean of its divisors is an integer number (85563).

2²⁸⁵²⁰⁵ is an apocalyptic number.

It is an amenable number.

285205 is a deficient number, since it is larger than the sum of its proper divisors (57047).

285205 is an equidigital number, since it uses as much as digits as its factorization.

285205 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 57046.

The product of its (nonzero) digits is 800, while the sum is 22.

The square root of 285205 is about 534.0458781790. The cubic root of 285205 is about 65.8242185034.

Adding to 285205 its reverse (502582), we get a palindrome (787787).

The spelling of 285205 in words is "two hundred eighty-five thousand, two hundred five".