212212121221 has 4 divisors (see below), whose sum is σ = 212261928844. Its totient is φ = 212162313600.

The previous prime is 212212121203. The next prime is 212212121227. The reversal of 212212121221 is 122121212212.

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 193260468996 + 18951652225 = 439614^2 + 137665^2 .

It is a cyclic number.

It is not a de Polignac number, because 212212121221 - 2¹¹ = 212212119173 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (212212121227) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24897420 + ... + 24905941.

It is an arithmetic number, because the mean of its divisors is an integer number (53065482211).

Almost surely, 2^212212121221 is an apocalyptic number.

It is an amenable number.

212212121221 is a deficient number, since it is larger than the sum of its proper divisors (49807623).

212212121221 is an equidigital number, since it uses as much as digits as its factorization.

212212121221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49807622.

The product of its digits is 128, while the sum is 19.

Adding to 212212121221 its reverse (122121212212), we get a palindrome (334333333433).

Subtracting from 212212121221 its reverse (122121212212), we obtain a palindrome (90090909009).

It can be divided in two parts, 2 and 12212121221, that multiplied together give a palindrome (24424242442).

The spelling of 212212121221 in words is "two hundred twelve billion, two hundred twelve million, one hundred twenty-one thousand, two hundred twenty-one".