21088224 has 72 divisors (see below), whose sum is σ = 61621560. Its totient is φ = 6835968.

The previous prime is 21088219. The next prime is 21088237. The reversal of 21088224 is 42288012.

It is a tau number, because it is divible by the number of its divisors (72).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9667 + ... + 11645.

It is an arithmetic number, because the mean of its divisors is an integer number (855855).

Almost surely, 2^21088224 is an apocalyptic number.

21088224 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 21088224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30810780).

21088224 is an abundant number, since it is smaller than the sum of its proper divisors (40533336).

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

21088224 is a wasteful number, since it uses less digits than its factorization.

21088224 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2032 (or 2021 counting only the distinct ones).

The product of its (nonzero) digits is 2048, while the sum is 27.

The square root of 21088224 is about 4592.1916336320. The cubic root of 21088224 is about 276.2782323405.

It can be divided in two parts, 21088 and 224, that added together give a palindrome (21312).

The spelling of 21088224 in words is "twenty-one million, eighty-eight thousand, two hundred twenty-four".