21103424 has 28 divisors (see below), whose sum is σ = 42460164. Its totient is φ = 10404864.

The previous prime is 21103403. The next prime is 21103441. The reversal of 21103424 is 42430112.

It can be written as a sum of positive squares in 2 ways, for example, as 4129024 + 16974400 = 2032^2 + 4120^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2414 + ... + 6930.

Almost surely, 2^21103424 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 21103424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21230082).

21103424 is an abundant number, since it is smaller than the sum of its proper divisors (21356740).

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

21103424 is an equidigital number, since it uses as much as digits as its factorization.

21103424 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4602 (or 4592 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21103424 is about 4593.8463187181. The cubic root of 21103424 is about 276.3445951374.

Adding to 21103424 its reverse (42430112), we get a palindrome (63533536).

The spelling of 21103424 in words is "twenty-one million, one hundred three thousand, four hundred twenty-four".