25569172781 has 2 divisors, whose sum is σ = 25569172782. Its totient is φ = 25569172780.

The previous prime is 25569172757. The next prime is 25569172817. The reversal of 25569172781 is 18727196552.

Together with next prime (25569172817) it forms an Ormiston pair, because they use the same digits, order apart.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14576698756 + 10992474025 = 120734^2 + 104845^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-25569172781 is a prime.

It is a super-2 number, since 2×25569172781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (25569171781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12784586390 + 12784586391.

It is an arithmetic number, because the mean of its divisors is an integer number (12784586391).

Almost surely, 2^25569172781 is an apocalyptic number.

It is an amenable number.

25569172781 is a deficient number, since it is larger than the sum of its proper divisors (1).

25569172781 is an equidigital number, since it uses as much as digits as its factorization.

25569172781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2116800, while the sum is 53.

The spelling of 25569172781 in words is "twenty-five billion, five hundred sixty-nine million, one hundred seventy-two thousand, seven hundred eighty-one".