21844728 has 96 divisors (see below), whose sum is σ = 65061360. Its totient is φ = 6842880.

The previous prime is 21844727. The next prime is 21844729. The reversal of 21844728 is 82744812.

21844728 is a `hidden beast` number, since 2 + 184 + 472 + 8 = 666.

It is an interprime number because it is at equal distance from previous prime (21844727) and next prime (21844729).

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

It is a junction number, because it is equal to n+sod(n) for n = 21844692 and 21844701.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21844727) 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, 32718 + ... + 33378.

Almost surely, 2^21844728 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 21844728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32530680).

21844728 is an abundant number, since it is smaller than the sum of its proper divisors (43216632).

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

21844728 is a wasteful number, since it uses less digits than its factorization.

21844728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 699 (or 683 counting only the distinct ones).

The product of its digits is 28672, while the sum is 36.

The square root of 21844728 is about 4673.8344001473. The cubic root of 21844728 is about 279.5431666245.

The spelling of 21844728 in words is "twenty-one million, eight hundred forty-four thousand, seven hundred twenty-eight".