25431663311521 has 2 divisors, whose sum is σ = 25431663311522. Its totient is φ = 25431663311520.

The previous prime is 25431663311491. The next prime is 25431663311563. The reversal of 25431663311521 is 12511336613452.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18994081568400 + 6437581743121 = 4358220^2 + 2537239^2 .

It is a cyclic number.

It is not a de Polignac number, because 25431663311521 - 2⁵ = 25431663311489 is a prime.

It is not a weakly prime, because it can be changed into another prime (25431663311221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12715831655760 + 12715831655761.

It is an arithmetic number, because the mean of its divisors is an integer number (12715831655761).

Almost surely, 2^{25431663311521} is an apocalyptic number.

It is an amenable number.

25431663311521 is a deficient number, since it is larger than the sum of its proper divisors (1).

25431663311521 is an equidigital number, since it uses as much as digits as its factorization.

25431663311521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 388800, while the sum is 43.

Adding to 25431663311521 its reverse (12511336613452), we get a palindrome (37942999924973).

The spelling of 25431663311521 in words is "twenty-five trillion, four hundred thirty-one billion, six hundred sixty-three million, three hundred eleven thousand, five hundred twenty-one".