21284224 has 32 divisors (see below), whose sum is σ = 45667440. Its totient is φ = 9822720.

The previous prime is 21284189. The next prime is 21284227. The reversal of 21284224 is 42248212.

It is a tau number, because it is divible by the number of its divisors (32).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21284227) 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, 4732 + ... + 8059.

Almost surely, 2^21284224 is an apocalyptic number.

It is an amenable number.

21284224 is an abundant number, since it is smaller than the sum of its proper divisors (24383216).

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

21284224 is a wasteful number, since it uses less digits than its factorization.

21284224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12818 (or 12806 counting only the distinct ones).

The product of its digits is 2048, while the sum is 25.

The square root of 21284224 is about 4613.4828492149. The cubic root of 21284224 is about 277.1315305434.

The spelling of 21284224 in words is "twenty-one million, two hundred eighty-four thousand, two hundred twenty-four".