25591 has 4 divisors (see below), whose sum is σ = 25912. Its totient is φ = 25272.

The previous prime is 25589. The next prime is 25601. The reversal of 25591 is 19552.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 25591 - 2¹ = 25589 is a prime.

It is a Duffinian number.

25591 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76 + ... + 238.

It is an arithmetic number, because the mean of its divisors is an integer number (6478).

2²⁵⁵⁹¹ is an apocalyptic number.

25591 is a deficient number, since it is larger than the sum of its proper divisors (321).

25591 is a wasteful number, since it uses less digits than its factorization.

25591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 320.

The product of its digits is 450, while the sum is 22.

The square root of 25591 is about 159.9718725276. The cubic root of 25591 is about 29.4687978048.

It can be divided in two parts, 25 and 591, that added together give a palindrome (616).

The spelling of 25591 in words is "twenty-five thousand, five hundred ninety-one".