1221221022221 has 2 divisors, whose sum is σ = 1221221022222. Its totient is φ = 1221221022220.

The previous prime is 1221221022181. The next prime is 1221221022239. The reversal of 1221221022221 is 1222201221221.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 831078373225 + 390142648996 = 911635^2 + 624614^2 .

It is an emirp because it is prime and its reverse (1222201221221) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1221221022221 - 2⁶ = 1221221022157 is a prime.

It is a super-2 number, since 2×1221221022221² (a number of 25 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 1221221022193 and 1221221022202.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1221221022821) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 610610511110 + 610610511111.

It is an arithmetic number, because the mean of its divisors is an integer number (610610511111).

Almost surely, 2^{1221221022221} is an apocalyptic number.

It is an amenable number.

1221221022221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1221221022221 is an equidigital number, since it uses as much as digits as its factorization.

1221221022221 is an odious number, because the sum of its binary digits is odd.

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

Adding to 1221221022221 its reverse (1222201221221), we get a palindrome (2443422243442).

The spelling of 1221221022221 in words is "one trillion, two hundred twenty-one billion, two hundred twenty-one million, twenty-two thousand, two hundred twenty-one".