2222222221 has 4 divisors (see below), whose sum is σ = 2247191100. Its totient is φ = 2197253344.

The previous prime is 2222222137. The next prime is 2222222243. The reversal of 2222222221 is 1222222222.

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 440538121 + 1781684100 = 20989^2 + 42210^2 .

It is a cyclic number.

It is not a de Polignac number, because 2222222221 - 2⁹ = 2222221709 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2222222291) 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, 12484306 + ... + 12484483.

It is an arithmetic number, because the mean of its divisors is an integer number (561797775).

Almost surely, 2^2222222221 is an apocalyptic number.

It is an amenable number.

2222222221 is a deficient number, since it is larger than the sum of its proper divisors (24968879).

2222222221 is an equidigital number, since it uses as much as digits as its factorization.

2222222221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24968878.

The product of its digits is 512, while the sum is 19.

The square root of 2222222221 is about 47140.4520661395. The cubic root of 2222222221 is about 1304.9558801504.

Adding to 2222222221 its reverse (1222222222), we get a palindrome (3444444443).

Subtracting from 2222222221 its reverse (1222222222), we obtain a palindrome (999999999).

The spelling of 2222222221 in words is "two billion, two hundred twenty-two million, two hundred twenty-two thousand, two hundred twenty-one".