25513031521 has 2 divisors, whose sum is σ = 25513031522. Its totient is φ = 25513031520.

The previous prime is 25513031519. The next prime is 25513031569. The reversal of 25513031521 is 12513031552.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16462173025 + 9050858496 = 128305^2 + 95136^2 .

It is a cyclic number.

It is not a de Polignac number, because 25513031521 - 2¹ = 25513031519 is a prime.

Together with 25513031519, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 25513031521.

It is not a weakly prime, because it can be changed into another prime (25513131521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12756515760 + 12756515761.

It is an arithmetic number, because the mean of its divisors is an integer number (12756515761).

Almost surely, 2^25513031521 is an apocalyptic number.

It is an amenable number.

25513031521 is a deficient number, since it is larger than the sum of its proper divisors (1).

25513031521 is an equidigital number, since it uses as much as digits as its factorization.

25513031521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4500, while the sum is 28.

The spelling of 25513031521 in words is "twenty-five billion, five hundred thirteen million, thirty-one thousand, five hundred twenty-one".