21323321 has 8 divisors (see below), whose sum is σ = 23129064. Its totient is φ = 19578880.

The previous prime is 21323311. The next prime is 21323371. The reversal of 21323321 is 12332312.

It can be written as a sum of positive squares in 4 ways, for example, as 2496400 + 18826921 = 1580^2 + 4339^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21323321 - 2¹⁰ = 21322297 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

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 21323321.

It is not an unprimeable number, because it can be changed into a prime (21323311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14600 + ... + 15993.

It is an arithmetic number, because the mean of its divisors is an integer number (2891133).

It is a self-describing number.

Almost surely, 2^21323321 is an apocalyptic number.

It is an amenable number.

21323321 is a deficient number, since it is larger than the sum of its proper divisors (1805743).

21323321 is a wasteful number, since it uses less digits than its factorization.

21323321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30651.

The product of its digits is 216, while the sum is 17.

The square root of 21323321 is about 4617.7181594376. The cubic root of 21323321 is about 277.3011144244.

Adding to 21323321 its reverse (12332312), we get a palindrome (33655633).

The spelling of 21323321 in words is "twenty-one million, three hundred twenty-three thousand, three hundred twenty-one".