25515197809 has 2 divisors, whose sum is σ = 25515197810. Its totient is φ = 25515197808.

The previous prime is 25515197797. The next prime is 25515197837. The reversal of 25515197809 is 90879151552.

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., 13835640625 + 11679557184 = 117625^2 + 108072^2 .

It is a cyclic number.

It is not a de Polignac number, because 25515197809 - 2¹⁷ = 25515066737 is a prime.

It is not a weakly prime, because it can be changed into another prime (25515197849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12757598904 + 12757598905.

It is an arithmetic number, because the mean of its divisors is an integer number (12757598905).

Almost surely, 2^25515197809 is an apocalyptic number.

It is an amenable number.

25515197809 is a deficient number, since it is larger than the sum of its proper divisors (1).

25515197809 is an equidigital number, since it uses as much as digits as its factorization.

25515197809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1134000, while the sum is 52.

The spelling of 25515197809 in words is "twenty-five billion, five hundred fifteen million, one hundred ninety-seven thousand, eight hundred nine".