21224443 has 4 divisors (see below), whose sum is σ = 21434688. Its totient is φ = 21014200.

The previous prime is 21224431. The next prime is 21224447. The reversal of 21224443 is 34442212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21224443 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21224447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 104971 + ... + 105172.

It is an arithmetic number, because the mean of its divisors is an integer number (5358672).

Almost surely, 2^21224443 is an apocalyptic number.

21224443 is a deficient number, since it is larger than the sum of its proper divisors (210245).

21224443 is a wasteful number, since it uses less digits than its factorization.

21224443 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 210244.

The product of its digits is 1536, while the sum is 22.

The square root of 21224443 is about 4606.9993488170. Note that the first 3 decimals coincide. The cubic root of 21224443 is about 276.8718274719.

Adding to 21224443 its reverse (34442212), we get a palindrome (55666655).

The spelling of 21224443 in words is "twenty-one million, two hundred twenty-four thousand, four hundred forty-three".