21244321 has 4 divisors (see below), whose sum is σ = 24279232. Its totient is φ = 18209412.

The previous prime is 21244309. The next prime is 21244367. The reversal of 21244321 is 12344212.

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-21244321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21244121) 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, 1517445 + ... + 1517458.

It is an arithmetic number, because the mean of its divisors is an integer number (6069808).

Almost surely, 2^21244321 is an apocalyptic number.

It is an amenable number.

21244321 is a deficient number, since it is larger than the sum of its proper divisors (3034911).

21244321 is an equidigital number, since it uses as much as digits as its factorization.

21244321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3034910.

The product of its digits is 384, while the sum is 19.

The square root of 21244321 is about 4609.1562134517. The cubic root of 21244321 is about 276.9582363498.

Adding to 21244321 its reverse (12344212), we get a palindrome (33588533).

The spelling of 21244321 in words is "twenty-one million, two hundred forty-four thousand, three hundred twenty-one".