25581231 has 32 divisors (see below), whose sum is σ = 42147840. Its totient is φ = 15228000.

The previous prime is 25581217. The next prime is 25581247. The reversal of 25581231 is 13218552.

It is a happy number.

It is not a de Polignac number, because 25581231 - 2¹⁰ = 25580207 is a prime.

It is a super-2 number, since 2×25581231² = 1308798758950722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 25581195 and 25581204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (25581211) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9706 + ... + 12056.

It is an arithmetic number, because the mean of its divisors is an integer number (1317120).

Almost surely, 2^25581231 is an apocalyptic number.

25581231 is a deficient number, since it is larger than the sum of its proper divisors (16566609).

25581231 is a wasteful number, since it uses less digits than its factorization.

25581231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2404 (or 2398 counting only the distinct ones).

The product of its digits is 2400, while the sum is 27.

The square root of 25581231 is about 5057.7891415123. The cubic root of 25581231 is about 294.6504756283.

Adding to 25581231 its reverse (13218552), we get a palindrome (38799783).

The spelling of 25581231 in words is "twenty-five million, five hundred eighty-one thousand, two hundred thirty-one".