21112011917 has 2 divisors, whose sum is σ = 21112011918. Its totient is φ = 21112011916.

The previous prime is 21112011889. The next prime is 21112012049. The reversal of 21112011917 is 71911021112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20550369316 + 561642601 = 143354^2 + 23699^2 .

It is a cyclic number.

It is not a de Polignac number, because 21112011917 - 2⁶ = 21112011853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21112011317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10556005958 + 10556005959.

It is an arithmetic number, because the mean of its divisors is an integer number (10556005959).

Almost surely, 2^21112011917 is an apocalyptic number.

It is an amenable number.

21112011917 is a deficient number, since it is larger than the sum of its proper divisors (1).

21112011917 is an equidigital number, since it uses as much as digits as its factorization.

21112011917 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 252, while the sum is 26.

The spelling of 21112011917 in words is "twenty-one billion, one hundred twelve million, eleven thousand, nine hundred seventeen".