21303424 has 32 divisors (see below), whose sum is σ = 42763500. Its totient is φ = 10570752.

The previous prime is 21303421. The next prime is 21303467. The reversal of 21303424 is 42430312.

It can be written as a sum of positive squares in 2 ways, for example, as 16321600 + 4981824 = 4040^2 + 2232^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is not an unprimeable number, because it can be changed into a prime (21303421) 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, 18514 + ... + 19630.

Almost surely, 2^21303424 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 21303424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21381750).

21303424 is an abundant number, since it is smaller than the sum of its proper divisors (21460076).

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

21303424 is a wasteful number, since it uses less digits than its factorization.

21303424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1280 (or 1268 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 19.

The square root of 21303424 is about 4615.5632375692. The cubic root of 21303424 is about 277.2148367866.

Adding to 21303424 its reverse (42430312), we get a palindrome (63733736).

The spelling of 21303424 in words is "twenty-one million, three hundred three thousand, four hundred twenty-four".