21284384 has 72 divisors (see below), whose sum is σ = 48263040. Its totient is φ = 9215360.

The previous prime is 21284381. The next prime is 21284387. The reversal of 21284384 is 48348212.

It is an interprime number because it is at equal distance from previous prime (21284381) and next prime (21284387).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a self number, because there is not a number n which added to its sum of digits gives 21284384.

It is not an unprimeable number, because it can be changed into a prime (21284381) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 88937 + ... + 89175.

It is an arithmetic number, because the mean of its divisors is an integer number (670320).

Almost surely, 2^21284384 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 21284384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24131520).

21284384 is an abundant number, since it is smaller than the sum of its proper divisors (26978656).

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

21284384 is a wasteful number, since it uses less digits than its factorization.

21284384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 294 (or 275 counting only the distinct ones).

The product of its digits is 12288, while the sum is 32.

The square root of 21284384 is about 4613.5001896608. The cubic root of 21284384 is about 277.1322249690.

The spelling of 21284384 in words is "twenty-one million, two hundred eighty-four thousand, three hundred eighty-four".