21221220220121 has 2 divisors, whose sum is σ = 21221220220122. Its totient is φ = 21221220220120.

The previous prime is 21221220220111. The next prime is 21221220220171. The reversal of 21221220220121 is 12102202212212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16069387064896 + 5151833155225 = 4008664^2 + 2269765^2 .

It is a cyclic number.

It is not a de Polignac number, because 21221220220121 - 2¹⁰ = 21221220219097 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21221220220093 and 21221220220102.

It is not a weakly prime, because it can be changed into another prime (21221220220111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610610110060 + 10610610110061.

It is an arithmetic number, because the mean of its divisors is an integer number (10610610110061).

Almost surely, 2^{21221220220121} is an apocalyptic number.

It is an amenable number.

21221220220121 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221220220121 is an equidigital number, since it uses as much as digits as its factorization.

21221220220121 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 256, while the sum is 20.

Adding to 21221220220121 its reverse (12102202212212), we get a palindrome (33323422432333).

The spelling of 21221220220121 in words is "twenty-one trillion, two hundred twenty-one billion, two hundred twenty million, two hundred twenty thousand, one hundred twenty-one".