21753224 has 8 divisors (see below), whose sum is σ = 40787310. Its totient is φ = 10876608.

The previous prime is 21753209. The next prime is 21753257. The reversal of 21753224 is 42235712.

It can be written as a sum of positive squares in only one way, i.e., 11628100 + 10125124 = 3410^2 + 3182^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a junction number, because it is equal to n+sod(n) for n = 21753193 and 21753202.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1359569 + ... + 1359584.

Almost surely, 2^21753224 is an apocalyptic number.

It is an amenable number.

21753224 is a deficient number, since it is larger than the sum of its proper divisors (19034086).

21753224 is a wasteful number, since it uses less digits than its factorization.

21753224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2719159 (or 2719155 counting only the distinct ones).

The product of its digits is 3360, while the sum is 26.

The square root of 21753224 is about 4664.0351628177. The cubic root of 21753224 is about 279.1523001245.

Adding to 21753224 its reverse (42235712), we get a palindrome (63988936).

The spelling of 21753224 in words is "twenty-one million, seven hundred fifty-three thousand, two hundred twenty-four".