21984144 has 120 divisors (see below), whose sum is σ = 71245440. Its totient is φ = 5789952.

The previous prime is 21984143. The next prime is 21984161. The reversal of 21984144 is 44148912.

It is a hoax number, since the sum of its digits (33) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21984143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30217 + ... + 30935.

It is an arithmetic number, because the mean of its divisors is an integer number (593712).

Almost surely, 2^21984144 is an apocalyptic number.

21984144 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 21984144, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35622720).

21984144 is an abundant number, since it is smaller than the sum of its proper divisors (49261296).

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

21984144 is a wasteful number, since it uses less digits than its factorization.

21984144 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 757 (or 744 counting only the distinct ones).

The product of its digits is 9216, while the sum is 33.

The square root of 21984144 is about 4688.7251998811. The cubic root of 21984144 is about 280.1366000145.

The spelling of 21984144 in words is "twenty-one million, nine hundred eighty-four thousand, one hundred forty-four".