21011221120217 has 2 divisors, whose sum is σ = 21011221120218. Its totient is φ = 21011221120216.

The previous prime is 21011221120199. The next prime is 21011221120223. The reversal of 21011221120217 is 71202112211012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12296657342281 + 8714563777936 = 3506659^2 + 2952044^2 .

It is a cyclic number.

It is not a de Polignac number, because 21011221120217 - 2⁴² = 16613174609113 is a prime.

It is a super-2 number, since 2×21011221120217² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21011221120192 and 21011221120201.

It is not a weakly prime, because it can be changed into another prime (21011221120117) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10505610560108 + 10505610560109.

It is an arithmetic number, because the mean of its divisors is an integer number (10505610560109).

Almost surely, 2^{21011221120217} is an apocalyptic number.

It is an amenable number.

21011221120217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21011221120217 is an equidigital number, since it uses as much as digits as its factorization.

21011221120217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 224, while the sum is 23.

Adding to 21011221120217 its reverse (71202112211012), we get a palindrome (92213333331229).

The spelling of 21011221120217 in words is "twenty-one trillion, eleven billion, two hundred twenty-one million, one hundred twenty thousand, two hundred seventeen".