25581521 has 4 divisors (see below), whose sum is σ = 29236032. Its totient is φ = 21927012.

The previous prime is 25581503. The next prime is 25581527. The reversal of 25581521 is 12518552.

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.

It is a cyclic number.

It is not a de Polignac number, because 25581521 - 2¹⁰ = 25580497 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (25581527) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1827245 + ... + 1827258.

It is an arithmetic number, because the mean of its divisors is an integer number (7309008).

Almost surely, 2^25581521 is an apocalyptic number.

It is an amenable number.

25581521 is a deficient number, since it is larger than the sum of its proper divisors (3654511).

25581521 is an equidigital number, since it uses as much as digits as its factorization.

25581521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3654510.

The product of its digits is 4000, while the sum is 29.

The square root of 25581521 is about 5057.8178100837. The cubic root of 25581521 is about 294.6515890529.

The spelling of 25581521 in words is "twenty-five million, five hundred eighty-one thousand, five hundred twenty-one".