21211222217 has 2 divisors, whose sum is σ = 21211222218. Its totient is φ = 21211222216.

The previous prime is 21211222189. The next prime is 21211222231. The reversal of 21211222217 is 71222211212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17421096121 + 3790126096 = 131989^2 + 61564^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211222217 - 2⁸ = 21211221961 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21211222192 and 21211222201.

It is not a weakly prime, because it can be changed into another prime (21211222117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605611108 + 10605611109.

It is an arithmetic number, because the mean of its divisors is an integer number (10605611109).

Almost surely, 2^21211222217 is an apocalyptic number.

It is an amenable number.

21211222217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211222217 is an equidigital number, since it uses as much as digits as its factorization.

21211222217 is an evil number, because the sum of its binary digits is even.

The product of its digits is 448, while the sum is 23.

Adding to 21211222217 its reverse (71222211212), we get a palindrome (92433433429).

The spelling of 21211222217 in words is "twenty-one billion, two hundred eleven million, two hundred twenty-two thousand, two hundred seventeen".