21333111221 has 4 divisors (see below), whose sum is σ = 21333418092. Its totient is φ = 21332804352.

The previous prime is 21333111203. The next prime is 21333111287. The reversal of 21333111221 is 12211133312.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 18498720100 + 2834391121 = 136010^2 + 53239^2 .

It is a cyclic number.

It is not a de Polignac number, because 21333111221 - 2¹⁸ = 21332849077 is a prime.

It is a super-2 number, since 2×21333111221² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21333111193 and 21333111202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21333111721) 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, 6215 + ... + 206651.

It is an arithmetic number, because the mean of its divisors is an integer number (5333354523).

Almost surely, 2^21333111221 is an apocalyptic number.

It is an amenable number.

21333111221 is a deficient number, since it is larger than the sum of its proper divisors (306871).

21333111221 is a wasteful number, since it uses less digits than its factorization.

21333111221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 306870.

The product of its digits is 216, while the sum is 20.

Adding to 21333111221 its reverse (12211133312), we get a palindrome (33544244533).

The spelling of 21333111221 in words is "twenty-one billion, three hundred thirty-three million, one hundred eleven thousand, two hundred twenty-one".