285581 has 4 divisors (see below), whose sum is σ = 286752. Its totient is φ = 284412.

The previous prime is 285569. The next prime is 285599. The reversal of 285581 is 185582.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 185582 = 2 ⋅92791.

It is a cyclic number.

It is not a de Polignac number, because 285581 - 2⁶ = 285517 is a prime.

It is a super-3 number, since 3×285581³ = 69872966957333823, which contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 285581.

It is not an unprimeable number, because it can be changed into a prime (285521) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 65 + ... + 758.

It is an arithmetic number, because the mean of its divisors is an integer number (71688).

2²⁸⁵⁵⁸¹ is an apocalyptic number.

It is an amenable number.

285581 is a deficient number, since it is larger than the sum of its proper divisors (1171).

285581 is an equidigital number, since it uses as much as digits as its factorization.

285581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1170.

The product of its digits is 3200, while the sum is 29.

The square root of 285581 is about 534.3977919116. The cubic root of 285581 is about 65.8531322529.

Subtracting from 285581 its reverse (185582), we obtain a palindrome (99999).

The spelling of 285581 in words is "two hundred eighty-five thousand, five hundred eighty-one".