22121220221 has 4 divisors (see below), whose sum is σ = 22123231932. Its totient is φ = 22119208512.

The previous prime is 22121220203. The next prime is 22121220223. The reversal of 22121220221 is 12202212122.

It is a happy number.

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 10027819321 + 12093400900 = 100139^2 + 109970^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-22121220221 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 22121220221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (22121220223) 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, 989270 + ... + 1011383.

It is an arithmetic number, because the mean of its divisors is an integer number (5530807983).

Almost surely, 2^22121220221 is an apocalyptic number.

It is an amenable number.

22121220221 is a deficient number, since it is larger than the sum of its proper divisors (2011711).

22121220221 is a wasteful number, since it uses less digits than its factorization.

22121220221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2011710.

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

Adding to 22121220221 its reverse (12202212122), we get a palindrome (34323432343).

The spelling of 22121220221 in words is "twenty-two billion, one hundred twenty-one million, two hundred twenty thousand, two hundred twenty-one".