212121120221 has 4 divisors (see below), whose sum is σ = 212130146844. Its totient is φ = 212112093600.

The previous prime is 212121120199. The next prime is 212121120227. The reversal of 212121120221 is 122021121212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 57720062500 + 154401057721 = 240250^2 + 392939^2 .

It is a cyclic number.

It is not a de Polignac number, because 212121120221 - 2¹⁸ = 212120858077 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 212121120221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212121120227) 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 in 3 ways as a sum of consecutive naturals, for example, 4477970 + ... + 4525091.

It is an arithmetic number, because the mean of its divisors is an integer number (53032536711).

Almost surely, 2^212121120221 is an apocalyptic number.

It is an amenable number.

212121120221 is a deficient number, since it is larger than the sum of its proper divisors (9026623).

212121120221 is an equidigital number, since it uses as much as digits as its factorization.

212121120221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9026622.

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

Adding to 212121120221 its reverse (122021121212), we get a palindrome (334142241433).

Subtracting from 212121120221 its reverse (122021121212), we obtain a palindrome (90099999009).

The spelling of 212121120221 in words is "two hundred twelve billion, one hundred twenty-one million, one hundred twenty thousand, two hundred twenty-one".