25618521 has 4 divisors (see below), whose sum is σ = 34158032. Its totient is φ = 17079012.

The previous prime is 25618519. The next prime is 25618529. The reversal of 25618521 is 12581652.

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 not a de Polignac number, because 25618521 - 2¹ = 25618519 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25618529) 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, 4269751 + ... + 4269756.

It is an arithmetic number, because the mean of its divisors is an integer number (8539508).

Almost surely, 2^25618521 is an apocalyptic number.

It is an amenable number.

25618521 is a deficient number, since it is larger than the sum of its proper divisors (8539511).

25618521 is an equidigital number, since it uses as much as digits as its factorization.

25618521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8539510.

The product of its digits is 4800, while the sum is 30.

The square root of 25618521 is about 5061.4741923673. The cubic root of 25618521 is about 294.7935777030.

Subtracting from 25618521 its product of digits (4800), we obtain a square (25613721 = 5061²).

The spelling of 25618521 in words is "twenty-five million, six hundred eighteen thousand, five hundred twenty-one".