25518517261 has 2 divisors, whose sum is σ = 25518517262. Its totient is φ = 25518517260.

The previous prime is 25518517231. The next prime is 25518517279. The reversal of 25518517261 is 16271581552.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23215093225 + 2303424036 = 152365^2 + 47994^2 .

It is a cyclic number.

It is not a de Polignac number, because 25518517261 - 2¹⁵ = 25518484493 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25518517231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12759258630 + 12759258631.

It is an arithmetic number, because the mean of its divisors is an integer number (12759258631).

Almost surely, 2^25518517261 is an apocalyptic number.

It is an amenable number.

25518517261 is a deficient number, since it is larger than the sum of its proper divisors (1).

25518517261 is an equidigital number, since it uses as much as digits as its factorization.

25518517261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 168000, while the sum is 43.

The spelling of 25518517261 in words is "twenty-five billion, five hundred eighteen million, five hundred seventeen thousand, two hundred sixty-one".