25517638981 has 2 divisors, whose sum is σ = 25517638982. Its totient is φ = 25517638980.

The previous prime is 25517638969. The next prime is 25517639009. The reversal of 25517638981 is 18983671552.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25405490881 + 112148100 = 159391^2 + 10590^2 .

It is a cyclic number.

It is not a de Polignac number, because 25517638981 - 2¹¹ = 25517636933 is a prime.

It is a super-2 number, since 2×25517638981² (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 (25517638921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 12758819490 + 12758819491.

It is an arithmetic number, because the mean of its divisors is an integer number (12758819491).

Almost surely, 2^25517638981 is an apocalyptic number.

It is an amenable number.

25517638981 is a deficient number, since it is larger than the sum of its proper divisors (1).

25517638981 is an equidigital number, since it uses as much as digits as its factorization.

25517638981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3628800, while the sum is 55.

The spelling of 25517638981 in words is "twenty-five billion, five hundred seventeen million, six hundred thirty-eight thousand, nine hundred eighty-one".