21321824 has 24 divisors (see below), whose sum is σ = 42391440. Its totient is φ = 10555776.

The previous prime is 21321821. The next prime is 21321829. The reversal of 21321824 is 42812312.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21321824.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321821) 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, 62 + ... + 6530.

It is an arithmetic number, because the mean of its divisors is an integer number (1766310).

Almost surely, 2^21321824 is an apocalyptic number.

It is an amenable number.

21321824 is a deficient number, since it is larger than the sum of its proper divisors (21069616).

21321824 is a wasteful number, since it uses less digits than its factorization.

21321824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6582 (or 6574 counting only the distinct ones).

The product of its digits is 768, while the sum is 23.

The square root of 21321824 is about 4617.5560635470. The cubic root of 21321824 is about 277.2946249806.

The spelling of 21321824 in words is "twenty-one million, three hundred twenty-one thousand, eight hundred twenty-four".