25540561 has 4 divisors (see below), whose sum is σ = 26421300. Its totient is φ = 24659824.

The previous prime is 25540549. The next prime is 25540591. The reversal of 25540561 is 16504552.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 18147600 + 7392961 = 4260^2 + 2719^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25540561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (25540531) 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, 440326 + ... + 440383.

It is an arithmetic number, because the mean of its divisors is an integer number (6605325).

Almost surely, 2^25540561 is an apocalyptic number.

It is an amenable number.

25540561 is a deficient number, since it is larger than the sum of its proper divisors (880739).

25540561 is an equidigital number, since it uses as much as digits as its factorization.

25540561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 880738.

The product of its (nonzero) digits is 6000, while the sum is 28.

The square root of 25540561 is about 5053.7670108544. The cubic root of 25540561 is about 294.4942440142.

The spelling of 25540561 in words is "twenty-five million, five hundred forty thousand, five hundred sixty-one".