25561309 has 2 divisors, whose sum is σ = 25561310. Its totient is φ = 25561308.

The previous prime is 25561301. The next prime is 25561313. The reversal of 25561309 is 90316552.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17665209 + 7896100 = 4203^2 + 2810^2 .

It is a cyclic number.

It is not a de Polignac number, because 25561309 - 2³ = 25561301 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25561301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12780654 + 12780655.

It is an arithmetic number, because the mean of its divisors is an integer number (12780655).

Almost surely, 2^25561309 is an apocalyptic number.

It is an amenable number.

25561309 is a deficient number, since it is larger than the sum of its proper divisors (1).

25561309 is an equidigital number, since it uses as much as digits as its factorization.

25561309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8100, while the sum is 31.

The square root of 25561309 is about 5055.8193203476. The cubic root of 25561309 is about 294.5739670448.

The spelling of 25561309 in words is "twenty-five million, five hundred sixty-one thousand, three hundred nine".