26581 has 4 divisors (see below), whose sum is σ = 28000. Its totient is φ = 25164.

The previous prime is 26573. The next prime is 26591. The reversal of 26581 is 18562.

26581 = 28² + 29² + ... + 46².

It is a happy number.

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 an emirpimes, since its reverse is a distinct semiprime: 18562 = 2 ⋅9281.

It is a cyclic number.

It is not a de Polignac number, because 26581 - 2³ = 26573 is a prime.

It is a super-2 number, since 2×26581² = 1413099122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (26501) 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, 681 + ... + 718.

It is an arithmetic number, because the mean of its divisors is an integer number (7000).

2²⁶⁵⁸¹ is an apocalyptic number.

It is an amenable number.

26581 is a deficient number, since it is larger than the sum of its proper divisors (1419).

26581 is a wasteful number, since it uses less digits than its factorization.

26581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1418.

The product of its digits is 480, while the sum is 22.

The square root of 26581 is about 163.0368056606. The cubic root of 26581 is about 29.8440050735.

The spelling of 26581 in words is "twenty-six thousand, five hundred eighty-one".