25861581 has 6 divisors (see below), whose sum is σ = 37355630. Its totient is φ = 17241048.

The previous prime is 25861553. The next prime is 25861643. The reversal of 25861581 is 18516852.

It can be written as a sum of positive squares in only one way, i.e., 25857225 + 4356 = 5085^2 + 66^2 .

It is a de Polignac number, because none of the positive numbers 2^k-25861581 is a prime.

It is a super-2 number, since 2×25861581² = 1337642743639122, 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 (25861501) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1436746 + ... + 1436763.

Almost surely, 2^25861581 is an apocalyptic number.

It is an amenable number.

25861581 is a deficient number, since it is larger than the sum of its proper divisors (11494049).

25861581 is a wasteful number, since it uses less digits than its factorization.

25861581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2873515 (or 2873512 counting only the distinct ones).

The product of its digits is 19200, while the sum is 36.

The square root of 25861581 is about 5085.4283005466. The cubic root of 25861581 is about 295.7229458061.

The spelling of 25861581 in words is "twenty-five million, eight hundred sixty-one thousand, five hundred eighty-one".