28581 has 8 divisors (see below), whose sum is σ = 43584. Its totient is φ = 16320.

The previous prime is 28579. The next prime is 28591. The reversal of 28581 is 18582.

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

It is not a de Polignac number, because 28581 - 2¹ = 28579 is a prime.

It is a super-2 number, since 2×28581² = 1633747122, which contains 22 as substring.

It is a Curzon number.

28581 is a lucky 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 28581.

It is not an unprimeable number, because it can be changed into a prime (28541) 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, 660 + ... + 701.

It is an arithmetic number, because the mean of its divisors is an integer number (5448).

2²⁸⁵⁸¹ is an apocalyptic number.

28581 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

28581 is a deficient number, since it is larger than the sum of its proper divisors (15003).

28581 is a wasteful number, since it uses less digits than its factorization.

28581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1371.

The product of its digits is 640, while the sum is 24.

The square root of 28581 is about 169.0591612424. The cubic root of 28581 is about 30.5744842617.

Subtracting from 28581 its reverse (18582), we obtain a palindrome (9999).

The spelling of 28581 in words is "twenty-eight thousand, five hundred eighty-one".