21423424 has 28 divisors (see below), whose sum is σ = 46378368. Its totient is φ = 9737600.

The previous prime is 21423421. The next prime is 21423487. The reversal of 21423424 is 42432412.

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 = 21423395 and 21423404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21423421) 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, 14512 + ... + 15919.

Almost surely, 2^21423424 is an apocalyptic number.

It is an amenable number.

21423424 is an abundant number, since it is smaller than the sum of its proper divisors (24954944).

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

21423424 is a wasteful number, since it uses less digits than its factorization.

21423424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30454 (or 30444 counting only the distinct ones).

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

The square root of 21423424 is about 4628.5444796394. The cubic root of 21423424 is about 277.7343700823.

Adding to 21423424 its reverse (42432412), we get a palindrome (63855836).

The spelling of 21423424 in words is "twenty-one million, four hundred twenty-three thousand, four hundred twenty-four".