2121222221 has 4 divisors (see below), whose sum is σ = 2157175200. Its totient is φ = 2085269244.

The previous prime is 2121222193. The next prime is 2121222227. The reversal of 2121222221 is 1222221212.

It is a happy number.

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 not a de Polignac number, because 2121222221 - 2¹⁴ = 2121205837 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 2121222221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2121222227) 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, 17976401 + ... + 17976518.

It is an arithmetic number, because the mean of its divisors is an integer number (539293800).

Almost surely, 2^2121222221 is an apocalyptic number.

It is an amenable number.

2121222221 is a deficient number, since it is larger than the sum of its proper divisors (35952979).

2121222221 is an equidigital number, since it uses as much as digits as its factorization.

2121222221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35952978.

The product of its digits is 128, while the sum is 17.

The square root of 2121222221 is about 46056.7282924004. The cubic root of 2121222221 is about 1284.8784819506.

Adding to 2121222221 its reverse (1222221212), we get a palindrome (3343443433).

The spelling of 2121222221 in words is "two billion, one hundred twenty-one million, two hundred twenty-two thousand, two hundred twenty-one".