21284424 has 96 divisors (see below), whose sum is σ = 68810400. Its totient is φ = 6078240.

The previous prime is 21284423. The next prime is 21284489. The reversal of 21284424 is 42448212.

21284424 is a `hidden beast` number, since 212 + 8 + 442 + 4 = 666.

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 not an unprimeable number, because it can be changed into a prime (21284423) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9579 + ... + 11589.

It is an arithmetic number, because the mean of its divisors is an integer number (716775).

Almost surely, 2^21284424 is an apocalyptic number.

21284424 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 21284424, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34405200).

21284424 is an abundant number, since it is smaller than the sum of its proper divisors (47525976).

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

21284424 is a wasteful number, since it uses less digits than its factorization.

21284424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2040 (or 2023 counting only the distinct ones).

The product of its digits is 4096, while the sum is 27.

The square root of 21284424 is about 4613.5045247621. The cubic root of 21284424 is about 277.1323985749.

The spelling of 21284424 in words is "twenty-one million, two hundred eighty-four thousand, four hundred twenty-four".