21221011221217 has 2 divisors, whose sum is σ = 21221011221218. Its totient is φ = 21221011221216.

The previous prime is 21221011221161. The next prime is 21221011221283. The reversal of 21221011221217 is 71212211012212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10898773166241 + 10322238054976 = 3301329^2 + 3212824^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221011221217 - 2⁷ = 21221011221089 is a prime.

It is a super-2 number, since 2×21221011221217² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21221011221191 and 21221011221200.

It is not a weakly prime, because it can be changed into another prime (21221011221317) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610505610608 + 10610505610609.

It is an arithmetic number, because the mean of its divisors is an integer number (10610505610609).

Almost surely, 2^{21221011221217} is an apocalyptic number.

It is an amenable number.

21221011221217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221011221217 is an equidigital number, since it uses as much as digits as its factorization.

21221011221217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 448, while the sum is 25.

Adding to 21221011221217 its reverse (71212211012212), we get a palindrome (92433222233429).

The spelling of 21221011221217 in words is "twenty-one trillion, two hundred twenty-one billion, eleven million, two hundred twenty-one thousand, two hundred seventeen".