1211220221021 has 2 divisors, whose sum is σ = 1211220221022. Its totient is φ = 1211220221020.

The previous prime is 1211220220999. The next prime is 1211220221033. The reversal of 1211220221021 is 1201220221121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 807850428025 + 403369792996 = 898805^2 + 635114^2 .

It is a cyclic number.

It is not a de Polignac number, because 1211220221021 - 2¹⁸ = 1211219958877 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1211220221821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 605610110510 + 605610110511.

It is an arithmetic number, because the mean of its divisors is an integer number (605610110511).

Almost surely, 2^{1211220221021} is an apocalyptic number.

It is an amenable number.

1211220221021 is a deficient number, since it is larger than the sum of its proper divisors (1).

1211220221021 is an equidigital number, since it uses as much as digits as its factorization.

1211220221021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 64, while the sum is 17.

Adding to 1211220221021 its reverse (1201220221121), we get a palindrome (2412440442142).

The spelling of 1211220221021 in words is "one trillion, two hundred eleven billion, two hundred twenty million, two hundred twenty-one thousand, twenty-one".