21122056717 has 2 divisors, whose sum is σ = 21122056718. Its totient is φ = 21122056716.

The previous prime is 21122056639. The next prime is 21122056721. The reversal of 21122056717 is 71765022112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13541045956 + 7581010761 = 116366^2 + 87069^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21122056717 is a prime.

It is a super-2 number, since 2×21122056717² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21122056727) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10561028358 + 10561028359.

It is an arithmetic number, because the mean of its divisors is an integer number (10561028359).

Almost surely, 2^21122056717 is an apocalyptic number.

It is an amenable number.

21122056717 is a deficient number, since it is larger than the sum of its proper divisors (1).

21122056717 is an equidigital number, since it uses as much as digits as its factorization.

21122056717 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11760, while the sum is 34.

Adding to 21122056717 its reverse (71765022112), we get a palindrome (92887078829).

The spelling of 21122056717 in words is "twenty-one billion, one hundred twenty-two million, fifty-six thousand, seven hundred seventeen".