21118125617 has 2 divisors, whose sum is σ = 21118125618. Its totient is φ = 21118125616.

The previous prime is 21118125599. The next prime is 21118125649. The reversal of 21118125617 is 71652181112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18522121216 + 2596004401 = 136096^2 + 50951^2 .

It is a cyclic number.

It is not a de Polignac number, because 21118125617 - 2⁸ = 21118125361 is a prime.

It is not a weakly prime, because it can be changed into another prime (21118125697) 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, 10559062808 + 10559062809.

It is an arithmetic number, because the mean of its divisors is an integer number (10559062809).

Almost surely, 2^21118125617 is an apocalyptic number.

It is an amenable number.

21118125617 is a deficient number, since it is larger than the sum of its proper divisors (1).

21118125617 is an equidigital number, since it uses as much as digits as its factorization.

21118125617 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6720, while the sum is 35.

The spelling of 21118125617 in words is "twenty-one billion, one hundred eighteen million, one hundred twenty-five thousand, six hundred seventeen".