21222021122221 has 2 divisors, whose sum is σ = 21222021122222. Its totient is φ = 21222021122220.

The previous prime is 21222021122209. The next prime is 21222021122227. The reversal of 21222021122221 is 12222112022212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14177190398121 + 7044830724100 = 3765261^2 + 2654210^2 .

It is a cyclic number.

It is not a de Polignac number, because 21222021122221 - 2²¹ = 21222019025069 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21222021122192 and 21222021122201.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21222021122227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10611010561110 + 10611010561111.

It is an arithmetic number, because the mean of its divisors is an integer number (10611010561111).

Almost surely, 2^{21222021122221} is an apocalyptic number.

It is an amenable number.

21222021122221 is a deficient number, since it is larger than the sum of its proper divisors (1).

21222021122221 is an equidigital number, since it uses as much as digits as its factorization.

21222021122221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 512, while the sum is 22.

Adding to 21222021122221 its reverse (12222112022212), we get a palindrome (33444133144433).

It can be divided in two parts, 2122202 and 1122221, that added together give a palindrome (3244423).

The spelling of 21222021122221 in words is "twenty-one trillion, two hundred twenty-two billion, twenty-one million, one hundred twenty-two thousand, two hundred twenty-one".