21444224 has 64 divisors (see below), whose sum is σ = 45441000. Its totient is φ = 10063872.

The previous prime is 21444223. The next prime is 21444233. The reversal of 21444224 is 42244412.

It can be written as a sum of positive squares in 4 ways, for example, as 20866624 + 577600 = 4568^2 + 760^2 .

It is a tau number, because it is divible by the number of its divisors (64).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21444224.

It is not an unprimeable number, because it can be changed into a prime (21444223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 196682 + ... + 196790.

Almost surely, 2^21444224 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21444224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22720500).

21444224 is an abundant number, since it is smaller than the sum of its proper divisors (23996776).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21444224 is a wasteful number, since it uses less digits than its factorization.

21444224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 205 (or 193 counting only the distinct ones).

The product of its digits is 2048, while the sum is 23.

The square root of 21444224 is about 4630.7908611813. The cubic root of 21444224 is about 277.8242250983.

Adding to 21444224 its reverse (42244412), we get a palindrome (63688636).

The spelling of 21444224 in words is "twenty-one million, four hundred forty-four thousand, two hundred twenty-four".