25659968021 has 2 divisors, whose sum is σ = 25659968022. Its totient is φ = 25659968020.

The previous prime is 25659968017. The next prime is 25659968029. The reversal of 25659968021 is 12086995652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 22049280100 + 3610687921 = 148490^2 + 60089^2 .

It is a cyclic number.

It is not a de Polignac number, because 25659968021 - 2² = 25659968017 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25659968029) 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, 12829984010 + 12829984011.

It is an arithmetic number, because the mean of its divisors is an integer number (12829984011).

Almost surely, 2^25659968021 is an apocalyptic number.

It is an amenable number.

25659968021 is a deficient number, since it is larger than the sum of its proper divisors (1).

25659968021 is an equidigital number, since it uses as much as digits as its factorization.

25659968021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2332800, while the sum is 53.

The spelling of 25659968021 in words is "twenty-five billion, six hundred fifty-nine million, nine hundred sixty-eight thousand, twenty-one".