21384648 has 80 divisors (see below), whose sum is σ = 60991260. Its totient is φ = 6998400.

The previous prime is 21384647. The next prime is 21384667. The reversal of 21384648 is 84648312.

21384648 is a `hidden beast` number, since 2 + 1 + 3 + 8 + 4 + 648 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 18818244 + 2566404 = 4338^2 + 1602^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

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 (21384647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 39258 + ... + 39798.

Almost surely, 2^21384648 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 21384648, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30495630).

21384648 is an abundant number, since it is smaller than the sum of its proper divisors (39606612).

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

21384648 is a wasteful number, since it uses less digits than its factorization.

21384648 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 620 (or 607 counting only the distinct ones).

The product of its digits is 36864, while the sum is 36.

The square root of 21384648 is about 4624.3537926936. The cubic root of 21384648 is about 277.5667041984.

It can be divided in two parts, 2138 and 4648, that added together give a triangular number (6786 = T₁₁₆).

The spelling of 21384648 in words is "twenty-one million, three hundred eighty-four thousand, six hundred forty-eight".