21328384 has 80 divisors (see below), whose sum is σ = 53228736. Its totient is φ = 8294400.

The previous prime is 21328381. The next prime is 21328399. The reversal of 21328384 is 48382312.

It is not an unprimeable number, because it can be changed into a prime (21328381) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39154 + ... + 39694.

Almost surely, 2^21328384 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 21328384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26614368).

21328384 is an abundant number, since it is smaller than the sum of its proper divisors (31900352).

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

21328384 is an equidigital number, since it uses as much as digits as its factorization.

21328384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 577 (or 561 counting only the distinct ones).

The product of its digits is 9216, while the sum is 31.

The square root of 21328384 is about 4618.2663413883. The cubic root of 21328384 is about 277.3230601060.

It can be divided in two parts, 21328 and 384, that added together give a palindrome (21712).

The spelling of 21328384 in words is "twenty-one million, three hundred twenty-eight thousand, three hundred eighty-four".