25138540681 has 2 divisors, whose sum is σ = 25138540682. Its totient is φ = 25138540680.

The previous prime is 25138540639. The next prime is 25138540727. The reversal of 25138540681 is 18604583152.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14960959225 + 10177581456 = 122315^2 + 100884^2 .

It is a cyclic number.

It is not a de Polignac number, because 25138540681 - 2¹⁵ = 25138507913 is a prime.

It is a super-2 number, since 2×25138540681² (a number of 22 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (25138540981) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12569270340 + 12569270341.

It is an arithmetic number, because the mean of its divisors is an integer number (12569270341).

Almost surely, 2^25138540681 is an apocalyptic number.

It is an amenable number.

25138540681 is a deficient number, since it is larger than the sum of its proper divisors (1).

25138540681 is an equidigital number, since it uses as much as digits as its factorization.

25138540681 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 230400, while the sum is 43.

The spelling of 25138540681 in words is "twenty-five billion, one hundred thirty-eight million, five hundred forty thousand, six hundred eighty-one".