1212121020221 has 2 divisors, whose sum is σ = 1212121020222. Its totient is φ = 1212121020220.

The previous prime is 1212121020203. The next prime is 1212121020223. The reversal of 1212121020221 is 1220201212121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 752748847321 + 459372172900 = 867611^2 + 677770^2 .

It is an emirp because it is prime and its reverse (1220201212121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1212121020221 - 2⁶ = 1212121020157 is a prime.

It is a Sophie Germain prime.

Together with 1212121020223, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1212121020221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1212121020223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 606060510110 + 606060510111.

It is an arithmetic number, because the mean of its divisors is an integer number (606060510111).

Almost surely, 2^{1212121020221} is an apocalyptic number.

It is an amenable number.

1212121020221 is a deficient number, since it is larger than the sum of its proper divisors (1).

1212121020221 is an equidigital number, since it uses as much as digits as its factorization.

1212121020221 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 1212121020221 its reverse (1220201212121), we get a palindrome (2432322232342).

The spelling of 1212121020221 in words is "one trillion, two hundred twelve billion, one hundred twenty-one million, twenty thousand, two hundred twenty-one".