212121012221 has 2 divisors, whose sum is σ = 212121012222. Its totient is φ = 212121012220.

The previous prime is 212121012163. The next prime is 212121012263. The reversal of 212121012221 is 122210121212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 141572340121 + 70548672100 = 376261^2 + 265610^2 .

It is a cyclic number.

It is not a de Polignac number, because 212121012221 - 2⁶ = 212121012157 is a prime.

It is a super-3 number, since 3×212121012221³ (a number of 35 digits) contains 333 as substring.

It is a Sophie Germain 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 212121012221.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (212121012821) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 106060506110 + 106060506111.

It is an arithmetic number, because the mean of its divisors is an integer number (106060506111).

Almost surely, 2^212121012221 is an apocalyptic number.

It is an amenable number.

212121012221 is a deficient number, since it is larger than the sum of its proper divisors (1).

212121012221 is an equidigital number, since it uses as much as digits as its factorization.

212121012221 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 212121012221 its reverse (122210121212), we get a palindrome (334331133433).

The spelling of 212121012221 in words is "two hundred twelve billion, one hundred twenty-one million, twelve thousand, two hundred twenty-one".