21223224 has 96 divisors (see below), whose sum is σ = 63498240. Its totient is φ = 6350400.

The previous prime is 21223219. The next prime is 21223261. The reversal of 21223224 is 42232212.

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

It is a nude number because it is divisible by every one of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21223197 and 21223206.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 100479 + ... + 100689.

It is an arithmetic number, because the mean of its divisors is an integer number (661440).

Almost surely, 2^21223224 is an apocalyptic number.

21223224 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 21223224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31749120).

21223224 is an abundant number, since it is smaller than the sum of its proper divisors (42275016).

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

21223224 is a wasteful number, since it uses less digits than its factorization.

21223224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 361 (or 354 counting only the distinct ones).

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

The square root of 21223224 is about 4606.8670482227. The cubic root of 21223224 is about 276.8665267718.

Adding to 21223224 its reverse (42232212), we get a palindrome (63455436).

It can be divided in two parts, 212 and 23224, that added together give a triangular number (23436 = T₂₁₆).

The spelling of 21223224 in words is "twenty-one million, two hundred twenty-three thousand, two hundred twenty-four".