285561 has 6 divisors (see below), whose sum is σ = 412490. Its totient is φ = 190368.

The previous prime is 285559. The next prime is 285569. The reversal of 285561 is 165582.

It can be written as a sum of positive squares in only one way, i.e., 281961 + 3600 = 531^2 + 60^2 .

It is not a de Polignac number, because 285561 - 2¹ = 285559 is a prime.

It is a Duffinian number.

285561 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (285569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 15856 + ... + 15873.

2²⁸⁵⁵⁶¹ is an apocalyptic number.

It is an amenable number.

285561 is a deficient number, since it is larger than the sum of its proper divisors (126929).

285561 is a wasteful number, since it uses less digits than its factorization.

285561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31735 (or 31732 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 285561 is about 534.3790789318. The cubic root of 285561 is about 65.8515949268.

It can be divided in two parts, 2855 and 61, that added together give a square (2916 = 54²).

The spelling of 285561 in words is "two hundred eighty-five thousand, five hundred sixty-one".