25561439 has 2 divisors, whose sum is σ = 25561440. Its totient is φ = 25561438.

The previous prime is 25561433. The next prime is 25561447. The reversal of 25561439 is 93416552.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 25561439 - 2²⁰ = 24512863 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 25561399 and 25561408.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25561433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12780719 + 12780720.

It is an arithmetic number, because the mean of its divisors is an integer number (12780720).

Almost surely, 2^25561439 is an apocalyptic number.

25561439 is a deficient number, since it is larger than the sum of its proper divisors (1).

25561439 is an equidigital number, since it uses as much as digits as its factorization.

25561439 is an evil number, because the sum of its binary digits is even.

The product of its digits is 32400, while the sum is 35.

The square root of 25561439 is about 5055.8321768033. The cubic root of 25561439 is about 294.5744664265.

The spelling of 25561439 in words is "twenty-five million, five hundred sixty-one thousand, four hundred thirty-nine".