21894444 has 72 divisors (see below), whose sum is σ = 65035152. Its totient is φ = 6122880.

The previous prime is 21894443. The next prime is 21894493. The reversal of 21894444 is 44449812.

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 = 21894399 and 21894408.

It is not an unprimeable number, because it can be changed into a prime (21894443) 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 23 ways as a sum of consecutive naturals, for example, 3022 + ... + 7274.

It is an arithmetic number, because the mean of its divisors is an integer number (903266).

Almost surely, 2^21894444 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 21894444, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32517576).

21894444 is an abundant number, since it is smaller than the sum of its proper divisors (43140708).

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

21894444 is a wasteful number, since it uses less digits than its factorization.

21894444 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4287 (or 4282 counting only the distinct ones).

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

The square root of 21894444 is about 4679.1499227958. The cubic root of 21894444 is about 279.7550749342.

The spelling of 21894444 in words is "twenty-one million, eight hundred ninety-four thousand, four hundred forty-four".