21533224 has 16 divisors (see below), whose sum is σ = 40792500. Its totient is φ = 10655232.

The previous prime is 21533219. The next prime is 21533227. The reversal of 21533224 is 42233512.

It can be written as a sum of positive squares in 2 ways, for example, as 21068100 + 465124 = 4590^2 + 682^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21533195 and 21533204.

It is not an unprimeable number, because it can be changed into a prime (21533227) 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, 13099 + ... + 14650.

Almost surely, 2^21533224 is an apocalyptic number.

It is an amenable number.

21533224 is a deficient number, since it is larger than the sum of its proper divisors (19259276).

21533224 is a wasteful number, since it uses less digits than its factorization.

21533224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27852 (or 27848 counting only the distinct ones).

The product of its digits is 1440, while the sum is 22.

The square root of 21533224 is about 4640.3905008092. The cubic root of 21533224 is about 278.2080460502.

Adding to 21533224 its reverse (42233512), we get a palindrome (63766736).

The spelling of 21533224 in words is "twenty-one million, five hundred thirty-three thousand, two hundred twenty-four".