21242304 has 112 divisors (see below), whose sum is σ = 65836800. Its totient is φ = 6697728.

The previous prime is 21242237. The next prime is 21242339. The reversal of 21242304 is 40324212.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32509 + ... + 33155.

Almost surely, 2^21242304 is an apocalyptic number.

21242304 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21242304, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32918400).

21242304 is an abundant number, since it is smaller than the sum of its proper divisors (44594496).

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

21242304 is a wasteful number, since it uses less digits than its factorization.

21242304 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 687 (or 671 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 18.

The square root of 21242304 is about 4608.9374046520. The cubic root of 21242304 is about 276.9494709885.

Adding to 21242304 its reverse (40324212), we get a palindrome (61566516).

The spelling of 21242304 in words is "twenty-one million, two hundred forty-two thousand, three hundred four".