1212121110221 has 4 divisors (see below), whose sum is σ = 1385281268832. Its totient is φ = 1038960951612.

The previous prime is 1212121110191. The next prime is 1212121110269. The reversal of 1212121110221 is 1220111212121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1212121110221 is a prime.

It is a Duffinian number.

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 1212121110221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1212121115221) 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, 86580079295 + ... + 86580079308.

It is an arithmetic number, because the mean of its divisors is an integer number (346320317208).

Almost surely, 2^{1212121110221} is an apocalyptic number.

It is an amenable number.

1212121110221 is a deficient number, since it is larger than the sum of its proper divisors (173160158611).

1212121110221 is an equidigital number, since it uses as much as digits as its factorization.

1212121110221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173160158610.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 1212121110221 its reverse (1220111212121), we get a palindrome (2432232322342).

The spelling of 1212121110221 in words is "one trillion, two hundred twelve billion, one hundred twenty-one million, one hundred ten thousand, two hundred twenty-one".