25231691921 has 2 divisors, whose sum is σ = 25231691922. Its totient is φ = 25231691920.

The previous prime is 25231691899. The next prime is 25231691959. The reversal of 25231691921 is 12919613252.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25189181521 + 42510400 = 158711^2 + 6520^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25231691921 is a prime.

It is not a weakly prime, because it can be changed into another prime (25231691971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12615845960 + 12615845961.

It is an arithmetic number, because the mean of its divisors is an integer number (12615845961).

Almost surely, 2^25231691921 is an apocalyptic number.

It is an amenable number.

25231691921 is a deficient number, since it is larger than the sum of its proper divisors (1).

25231691921 is an equidigital number, since it uses as much as digits as its factorization.

25231691921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 58320, while the sum is 41.

The spelling of 25231691921 in words is "twenty-five billion, two hundred thirty-one million, six hundred ninety-one thousand, nine hundred twenty-one".