25815409 has 2 divisors, whose sum is σ = 25815410. Its totient is φ = 25815408.

The previous prime is 25815397. The next prime is 25815421. The reversal of 25815409 is 90451852.

It is a balanced prime because it is at equal distance from previous prime (25815397) and next prime (25815421).

It can be written as a sum of positive squares in only one way, i.e., 25000000 + 815409 = 5000^2 + 903^2 .

It is a cyclic number.

It is not a de Polignac number, because 25815409 - 2¹⁵ = 25782641 is a prime.

It is not a weakly prime, because it can be changed into another prime (25815109) 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 as a sum of consecutive naturals, namely, 12907704 + 12907705.

It is an arithmetic number, because the mean of its divisors is an integer number (12907705).

Almost surely, 2^25815409 is an apocalyptic number.

It is an amenable number.

25815409 is a deficient number, since it is larger than the sum of its proper divisors (1).

25815409 is an equidigital number, since it uses as much as digits as its factorization.

25815409 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14400, while the sum is 34.

The square root of 25815409 is about 5080.8866352242. The cubic root of 25815409 is about 295.5468512134.

It can be divided in two parts, 25 and 815409, that multiplied together give a square (20385225 = 4515²).

The spelling of 25815409 in words is "twenty-five million, eight hundred fifteen thousand, four hundred nine".