21284648 has 64 divisors (see below), whose sum is σ = 50371200. Its totient is φ = 8190720.

The previous prime is 21284621. The next prime is 21284671. The reversal of 21284648 is 84648212.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 66986 + ... + 67302.

It is an arithmetic number, because the mean of its divisors is an integer number (787050).

Almost surely, 2^21284648 is an apocalyptic number.

21284648 is a gapful number since it is divisible by the number (28) 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 21284648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25185600).

21284648 is an abundant number, since it is smaller than the sum of its proper divisors (29086552).

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

21284648 is a wasteful number, since it uses less digits than its factorization.

21284648 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 450 (or 446 counting only the distinct ones).

The product of its digits is 24576, while the sum is 35.

The square root of 21284648 is about 4613.5288012540. The cubic root of 21284648 is about 277.1333707638.

It can be divided in two parts, 2128 and 4648, that added together give a palindrome (6776).

The spelling of 21284648 in words is "twenty-one million, two hundred eighty-four thousand, six hundred forty-eight".