21643324 has 24 divisors (see below), whose sum is σ = 38772720. Its totient is φ = 10568064.

The previous prime is 21643313. The next prime is 21643331. The reversal of 21643324 is 42334612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 68992 + ... + 69304.

It is an arithmetic number, because the mean of its divisors is an integer number (1615530).

Almost surely, 2^21643324 is an apocalyptic number.

It is an amenable number.

21643324 is a deficient number, since it is larger than the sum of its proper divisors (17129396).

21643324 is a wasteful number, since it uses less digits than its factorization.

21643324 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 669 (or 667 counting only the distinct ones).

The product of its digits is 3456, while the sum is 25.

The square root of 21643324 is about 4652.2386009318. The cubic root of 21643324 is about 278.6814021445.

Adding to 21643324 its reverse (42334612), we get a palindrome (63977936).

The spelling of 21643324 in words is "twenty-one million, six hundred forty-three thousand, three hundred twenty-four".