25122912781 has 2 divisors, whose sum is σ = 25122912782. Its totient is φ = 25122912780.

The previous prime is 25122912767. The next prime is 25122912799. The reversal of 25122912781 is 18721922152.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 24756190281 + 366722500 = 157341^2 + 19150^2 .

It is a cyclic number.

It is not a de Polignac number, because 25122912781 - 2⁷ = 25122912653 is a prime.

It is a super-2 number, since 2×25122912781² (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 (25122912721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12561456390 + 12561456391.

It is an arithmetic number, because the mean of its divisors is an integer number (12561456391).

Almost surely, 2^25122912781 is an apocalyptic number.

It is an amenable number.

25122912781 is a deficient number, since it is larger than the sum of its proper divisors (1).

25122912781 is an equidigital number, since it uses as much as digits as its factorization.

25122912781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 40320, while the sum is 40.

The spelling of 25122912781 in words is "twenty-five billion, one hundred twenty-two million, nine hundred twelve thousand, seven hundred eighty-one".