21284480 has 64 divisors (see below), whose sum is σ = 58164480. Its totient is φ = 7296000.

The previous prime is 21284423. The next prime is 21284489. The reversal of 21284480 is 8448212.

It is a tau number, because it is divible by the number of its divisors (64).

It is not an unprimeable number, because it can be changed into a prime (21284489) 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, 2105 + ... + 6855.

It is an arithmetic number, because the mean of its divisors is an integer number (908820).

Almost surely, 2^21284480 is an apocalyptic number.

21284480 is a gapful number since it is divisible by the number (20) 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 21284480, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29082240).

21284480 is an abundant number, since it is smaller than the sum of its proper divisors (36880000).

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

21284480 is an equidigital number, since it uses as much as digits as its factorization.

21284480 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4777 (or 4765 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 29.

The square root of 21284480 is about 4613.5105938970. The cubic root of 21284480 is about 277.1326416228.

The spelling of 21284480 in words is "twenty-one million, two hundred eighty-four thousand, four hundred eighty".