25491693209 has 2 divisors, whose sum is σ = 25491693210. Its totient is φ = 25491693208.

The previous prime is 25491693203. The next prime is 25491693257. The reversal of 25491693209 is 90239619452.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24909677584 + 582015625 = 157828^2 + 24125^2 .

It is a cyclic number.

It is not a de Polignac number, because 25491693209 - 2⁸ = 25491692953 is a prime.

It is not a weakly prime, because it can be changed into another prime (25491693203) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12745846604 + 12745846605.

It is an arithmetic number, because the mean of its divisors is an integer number (12745846605).

Almost surely, 2^25491693209 is an apocalyptic number.

It is an amenable number.

25491693209 is a deficient number, since it is larger than the sum of its proper divisors (1).

25491693209 is an equidigital number, since it uses as much as digits as its factorization.

25491693209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1049760, while the sum is 50.

The spelling of 25491693209 in words is "twenty-five billion, four hundred ninety-one million, six hundred ninety-three thousand, two hundred nine".