121212212221 has 4 divisors (see below), whose sum is σ = 121559525500. Its totient is φ = 120864898944.

The previous prime is 121212212197. The next prime is 121212212257. The reversal of 121212212221 is 122212212121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 122212212121 = 193 ⋅633223897.

It can be written as a sum of positive squares in 2 ways, for example, as 95607732025 + 25604480196 = 309205^2 + 160014^2 .

It is a cyclic number.

It is not a de Polignac number, because 121212212221 - 2⁵ = 121212212189 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 (121212212321) 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, 173656116 + ... + 173656813.

It is an arithmetic number, because the mean of its divisors is an integer number (30389881375).

Almost surely, 2^121212212221 is an apocalyptic number.

It is an amenable number.

121212212221 is a deficient number, since it is larger than the sum of its proper divisors (347313279).

121212212221 is an equidigital number, since it uses as much as digits as its factorization.

121212212221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 347313278.

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

Adding to 121212212221 its reverse (122212212121), we get a palindrome (243424424342).

The spelling of 121212212221 in words is "one hundred twenty-one billion, two hundred twelve million, two hundred twelve thousand, two hundred twenty-one".