25537081421 has 2 divisors, whose sum is σ = 25537081422. Its totient is φ = 25537081420.

The previous prime is 25537081399. The next prime is 25537081441. The reversal of 25537081421 is 12418073552.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14259703396 + 11277378025 = 119414^2 + 106195^2 .

It is a cyclic number.

It is not a de Polignac number, because 25537081421 - 2²² = 25532887117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25537081441) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12768540710 + 12768540711.

It is an arithmetic number, because the mean of its divisors is an integer number (12768540711).

Almost surely, 2^25537081421 is an apocalyptic number.

It is an amenable number.

25537081421 is a deficient number, since it is larger than the sum of its proper divisors (1).

25537081421 is an equidigital number, since it uses as much as digits as its factorization.

25537081421 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 67200, while the sum is 38.

The spelling of 25537081421 in words is "twenty-five billion, five hundred thirty-seven million, eighty-one thousand, four hundred twenty-one".