21047328 has 72 divisors (see below), whose sum is σ = 60501168. Its totient is φ = 6940032.

The previous prime is 21047317. The next prime is 21047333. The reversal of 21047328 is 82374012.

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

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 30475 + ... + 31157.

It is an arithmetic number, because the mean of its divisors is an integer number (840294).

Almost surely, 2^21047328 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 21047328, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30250584).

21047328 is an abundant number, since it is smaller than the sum of its proper divisors (39453840).

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

21047328 is a wasteful number, since it uses less digits than its factorization.

21047328 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 806 (or 795 counting only the distinct ones).

The product of its (nonzero) digits is 2688, while the sum is 27.

The square root of 21047328 is about 4587.7366968910. The cubic root of 21047328 is about 276.0995230248.

The spelling of 21047328 in words is "twenty-one million, forty-seven thousand, three hundred twenty-eight".