21222201221 has 12 divisors (see below), whose sum is σ = 24120870732. Its totient is φ = 18558681984.

The previous prime is 21222201199. The next prime is 21222201233. The reversal of 21222201221 is 12210222212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 11199988900 + 10022212321 = 105830^2 + 100111^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21222201221 is a prime.

It is a super-2 number, since 2×21222201221² (a number of 21 digits) contains 22 as substring.

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 21222201221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21222200221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2256356 + ... + 2265741.

It is an arithmetic number, because the mean of its divisors is an integer number (2010072561).

Almost surely, 2^21222201221 is an apocalyptic number.

It is an amenable number.

21222201221 is a deficient number, since it is larger than the sum of its proper divisors (2898669511).

21222201221 is a wasteful number, since it uses less digits than its factorization.

21222201221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4522148 (or 4522129 counting only the distinct ones).

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

Adding to 21222201221 its reverse (12210222212), we get a palindrome (33432423433).

The spelling of 21222201221 in words is "twenty-one billion, two hundred twenty-two million, two hundred one thousand, two hundred twenty-one".