21211085717 has 2 divisors, whose sum is σ = 21211085718. Its totient is φ = 21211085716.

The previous prime is 21211085683. The next prime is 21211085729. The reversal of 21211085717 is 71758011212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20440134961 + 770950756 = 142969^2 + 27766^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211085717 - 2¹⁰ = 21211084693 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211085117) 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, 10605542858 + 10605542859.

It is an arithmetic number, because the mean of its divisors is an integer number (10605542859).

Almost surely, 2^21211085717 is an apocalyptic number.

It is an amenable number.

21211085717 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211085717 is an equidigital number, since it uses as much as digits as its factorization.

21211085717 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7840, while the sum is 35.

Adding to 21211085717 its reverse (71758011212), we get a palindrome (92969096929).

The spelling of 21211085717 in words is "twenty-one billion, two hundred eleven million, eighty-five thousand, seven hundred seventeen".