21213323321 has 4 divisors (see below), whose sum is σ = 21215324532. Its totient is φ = 21211322112.

The previous prime is 21213323309. The next prime is 21213323377. The reversal of 21213323321 is 12332331212.

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 9261367696 + 11951955625 = 96236^2 + 109325^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213323321 - 2¹⁴ = 21213306937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21213323381) 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, 984620 + ... + 1005933.

It is an arithmetic number, because the mean of its divisors is an integer number (5303831133).

Almost surely, 2^21213323321 is an apocalyptic number.

It is an amenable number.

21213323321 is a deficient number, since it is larger than the sum of its proper divisors (2001211).

21213323321 is a wasteful number, since it uses less digits than its factorization.

21213323321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2001210.

The product of its digits is 1296, while the sum is 23.

Adding to 21213323321 its reverse (12332331212), we get a palindrome (33545654533).

The spelling of 21213323321 in words is "twenty-one billion, two hundred thirteen million, three hundred twenty-three thousand, three hundred twenty-one".