85581 has 12 divisors (see below), whose sum is σ = 127452. Its totient is φ = 55296.

The previous prime is 85577. The next prime is 85597. The reversal of 85581 is 18558.

85581 is a `hidden beast` number, since 85 + 581 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 81225 + 4356 = 285^2 + 66^2 .

It is not a de Polignac number, because 85581 - 2² = 85577 is a prime.

It is a super-2 number, since 2×85581² = 14648215122, which contains 22 as substring.

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (85531) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 205 + ... + 461.

It is an arithmetic number, because the mean of its divisors is an integer number (10621).

2⁸⁵⁵⁸¹ is an apocalyptic number.

It is an amenable number.

85581 is a deficient number, since it is larger than the sum of its proper divisors (41871).

85581 is a wasteful number, since it uses less digits than its factorization.

85581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300 (or 297 counting only the distinct ones).

The product of its digits is 1600, while the sum is 27.

The square root of 85581 is about 292.5423046330. The cubic root of 85581 is about 44.0682480807.

It can be divided in two parts, 85 and 581, that added together give a palindrome (666).

The spelling of 85581 in words is "eighty-five thousand, five hundred eighty-one".