21984456 has 64 divisors (see below), whose sum is σ = 61125120. Its totient is φ = 6543360.

The previous prime is 21984449. The next prime is 21984467. The reversal of 21984456 is 65448912.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 8536 + ... + 10808.

It is an arithmetic number, because the mean of its divisors is an integer number (955080).

Almost surely, 2^21984456 is an apocalyptic number.

21984456 is a gapful number since it is divisible by the number (26) 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 21984456, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30562560).

21984456 is an abundant number, since it is smaller than the sum of its proper divisors (39140664).

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

21984456 is a wasteful number, since it uses less digits than its factorization.

21984456 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2326 (or 2322 counting only the distinct ones).

The product of its digits is 69120, while the sum is 39.

The square root of 21984456 is about 4688.7584710667. The cubic root of 21984456 is about 280.1379252455.

The spelling of 21984456 in words is "twenty-one million, nine hundred eighty-four thousand, four hundred fifty-six".