21245224 has 96 divisors (see below), whose sum is σ = 54583200. Its totient is φ = 7620480.

The previous prime is 21245221. The next prime is 21245227. The reversal of 21245224 is 42254212.

It is an interprime number because it is at equal distance from previous prime (21245221) and next prime (21245227).

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 = 21245195 and 21245204.

It is not an unprimeable number, because it can be changed into a prime (21245221) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 55867 + ... + 56245.

It is an arithmetic number, because the mean of its divisors is an integer number (568575).

Almost surely, 2^21245224 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 21245224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27291600).

21245224 is an abundant number, since it is smaller than the sum of its proper divisors (33337976).

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

21245224 is a wasteful number, since it uses less digits than its factorization.

21245224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 423 (or 412 counting only the distinct ones).

The product of its digits is 1280, while the sum is 22.

The square root of 21245224 is about 4609.2541696027. The cubic root of 21245224 is about 276.9621603748.

Adding to 21245224 its reverse (42254212), we get a palindrome (63499436).

The spelling of 21245224 in words is "twenty-one million, two hundred forty-five thousand, two hundred twenty-four".