22581 has 12 divisors (see below), whose sum is σ = 35308. Its totient is φ = 13824.

The previous prime is 22573. The next prime is 22613. The reversal of 22581 is 18522.

22581 = T₂₈ + T₂₉ + ... + T₅₃.

22581 = 16² + 17² + ... + 41².

It can be written as a sum of positive squares in 2 ways, for example, as 4356 + 18225 = 66^2 + 135^2 .

It is not a de Polignac number, because 22581 - 2³ = 22573 is a prime.

It is a super-2 number, since 2×22581² = 1019803122, which contains 22 as substring.

It is a plaindrome in base 7.

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 22581.

It is not an unprimeable number, because it can be changed into a prime (22501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21 + ... + 213.

2²²⁵⁸¹ is an apocalyptic number.

It is an amenable number.

22581 is a deficient number, since it is larger than the sum of its proper divisors (12727).

22581 is a wasteful number, since it uses less digits than its factorization.

22581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212 (or 209 counting only the distinct ones).

The product of its digits is 160, while the sum is 18.

The square root of 22581 is about 150.2697574364. The cubic root of 22581 is about 28.2649175918.

It can be divided in two parts, 225 and 81, that multiplied together give a square (18225 = 135²).

The spelling of 22581 in words is "twenty-two thousand, five hundred eighty-one".