21268224 has 144 divisors (see below), whose sum is σ = 66961440. Its totient is φ = 6635520.

The previous prime is 21268213. The next prime is 21268231. The reversal of 21268224 is 42286212.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (144).

It is a super-2 number, since 2×21268224² = 904674704228352, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 117414 + ... + 117594.

It is an arithmetic number, because the mean of its divisors is an integer number (465010).

Almost surely, 2^21268224 is an apocalyptic number.

21268224 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 21268224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33480720).

21268224 is an abundant number, since it is smaller than the sum of its proper divisors (45693216).

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

21268224 is a wasteful number, since it uses less digits than its factorization.

21268224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 223 (or 203 counting only the distinct ones).

The product of its digits is 3072, while the sum is 27.

The square root of 21268224 is about 4611.7484753616. The cubic root of 21268224 is about 277.0620703955.

The spelling of 21268224 in words is "twenty-one million, two hundred sixty-eight thousand, two hundred twenty-four".