21043424 has 12 divisors (see below), whose sum is σ = 41429304. Its totient is φ = 10521696.

The previous prime is 21043423. The next prime is 21043441. The reversal of 21043424 is 42434012.

It is a junction number, because it is equal to n+sod(n) for n = 21043396 and 21043405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21043423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 328772 + ... + 328835.

It is an arithmetic number, because the mean of its divisors is an integer number (3452442).

Almost surely, 2^21043424 is an apocalyptic number.

It is an amenable number.

21043424 is a deficient number, since it is larger than the sum of its proper divisors (20385880).

21043424 is an equidigital number, since it uses as much as digits as its factorization.

21043424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 657617 (or 657609 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 20.

The square root of 21043424 is about 4587.3111950248. The cubic root of 21043424 is about 276.0824510369.

Adding to 21043424 its reverse (42434012), we get a palindrome (63477436).

It can be divided in two parts, 210 and 43424, that added together give a palindrome (43634).

The spelling of 21043424 in words is "twenty-one million, forty-three thousand, four hundred twenty-four".