25506821537 has 2 divisors, whose sum is σ = 25506821538. Its totient is φ = 25506821536.

The previous prime is 25506821503. The next prime is 25506821563. The reversal of 25506821537 is 73512860552.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15276712801 + 10230108736 = 123599^2 + 101144^2 .

It is a cyclic number.

It is not a de Polignac number, because 25506821537 - 2²⁸ = 25238386081 is a prime.

It is not a weakly prime, because it can be changed into another prime (25506821597) 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, 12753410768 + 12753410769.

It is an arithmetic number, because the mean of its divisors is an integer number (12753410769).

Almost surely, 2^25506821537 is an apocalyptic number.

It is an amenable number.

25506821537 is a deficient number, since it is larger than the sum of its proper divisors (1).

25506821537 is an equidigital number, since it uses as much as digits as its factorization.

25506821537 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 504000, while the sum is 44.

The spelling of 25506821537 in words is "twenty-five billion, five hundred six million, eight hundred twenty-one thousand, five hundred thirty-seven".