21344321 has 4 divisors (see below), whose sum is σ = 21356544. Its totient is φ = 21332100.

The previous prime is 21344311. The next prime is 21344339. The reversal of 21344321 is 12344312.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21344321 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21344293 and 21344302.

It is not an unprimeable number, because it can be changed into a prime (21344311) 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, 2945 + ... + 7166.

It is an arithmetic number, because the mean of its divisors is an integer number (5339136).

Almost surely, 2^21344321 is an apocalyptic number.

It is an amenable number.

21344321 is a deficient number, since it is larger than the sum of its proper divisors (12223).

21344321 is a wasteful number, since it uses less digits than its factorization.

21344321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12222.

The product of its digits is 576, while the sum is 20.

The square root of 21344321 is about 4619.9914502085. The cubic root of 21344321 is about 277.3921167089.

Adding to 21344321 its reverse (12344312), we get a palindrome (33688633).

Subtracting from 21344321 its reverse (12344312), we obtain a palindrome (9000009).

The spelling of 21344321 in words is "twenty-one million, three hundred forty-four thousand, three hundred twenty-one".