21324424 has 32 divisors (see below), whose sum is σ = 44245440. Its totient is φ = 9553600.

The previous prime is 21324421. The next prime is 21324451. The reversal of 21324424 is 42442312.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a junction number, because it is equal to n+sod(n) for n = 21324395 and 21324404.

It is not an unprimeable number, because it can be changed into a prime (21324421) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4542 + ... + 7954.

It is an arithmetic number, because the mean of its divisors is an integer number (1382670).

Almost surely, 2^21324424 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21324424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22122720).

21324424 is an abundant number, since it is smaller than the sum of its proper divisors (22921016).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21324424 is a wasteful number, since it uses less digits than its factorization.

21324424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3501 (or 3497 counting only the distinct ones).

The product of its digits is 1536, while the sum is 22.

The square root of 21324424 is about 4617.8375891753. The cubic root of 21324424 is about 277.3058956974.

Adding to 21324424 its reverse (42442312), we get a palindrome (63766736).

It can be divided in two parts, 2132 and 4424, that added together give a palindrome (6556).

The spelling of 21324424 in words is "twenty-one million, three hundred twenty-four thousand, four hundred twenty-four".