21213332321 has 4 divisors (see below), whose sum is σ = 21260578500. Its totient is φ = 21166086144.

The previous prime is 21213332317. The next prime is 21213332323. The reversal of 21213332321 is 12323331212.

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 11005059025 + 10208273296 = 104905^2 + 101036^2 .

It is a cyclic number.

It is not a de Polignac number, because 21213332321 - 2² = 21213332317 is a prime.

It is a super-2 number, since 2×21213332321² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21213332323) 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, 23622416 + ... + 23623313.

It is an arithmetic number, because the mean of its divisors is an integer number (5315144625).

Almost surely, 2^21213332321 is an apocalyptic number.

It is an amenable number.

21213332321 is a deficient number, since it is larger than the sum of its proper divisors (47246179).

21213332321 is an equidigital number, since it uses as much as digits as its factorization.

21213332321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47246178.

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

Adding to 21213332321 its reverse (12323331212), we get a palindrome (33536663533).

The spelling of 21213332321 in words is "twenty-one billion, two hundred thirteen million, three hundred thirty-two thousand, three hundred twenty-one".