21724324 has 12 divisors (see below), whose sum is σ = 38056284. Its totient is φ = 10851104.

The previous prime is 21724321. The next prime is 21724333. The reversal of 21724324 is 42342712.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 7661824 + 14062500 = 2768^2 + 3750^2 .

It is not an unprimeable number, because it can be changed into a prime (21724321) by changing a digit.

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 in 3 ways as a sum of consecutive naturals, for example, 2982 + ... + 7234.

It is an arithmetic number, because the mean of its divisors is an integer number (3171357).

Almost surely, 2^21724324 is an apocalyptic number.

It is an amenable number.

21724324 is a deficient number, since it is larger than the sum of its proper divisors (16331960).

21724324 is a wasteful number, since it uses less digits than its factorization.

21724324 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5534 (or 5532 counting only the distinct ones).

The product of its digits is 2688, while the sum is 25.

The square root of 21724324 is about 4660.9359575090. The cubic root of 21724324 is about 279.0286237938.

The spelling of 21724324 in words is "twenty-one million, seven hundred twenty-four thousand, three hundred twenty-four".