21591823 divided by 859 
Our goal is to divide 21591823 by 859.

Step 1:
The number 859 fits into 2 0 times, leaving a remainder of 2.
Record the quotient 0 as the next digit in the result. 
Result so far: 0.0
The remainder is 2 after subtracting 0 from 2.
Take the next digit (1) from the dividend and append it to 2, then repeat: 21 / 859

Advancing to step 2:
859 goes into 21 0 times with a remainder of 21.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Deduct 0 from 21 and we're left with 21.
Bring next digit (5) of the dividend behind the 21 and repeat the process: 215 / 859

Moving on to step 3:
859 can be fit into 215 0 times, resulting in a remainder of 215.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtracting 0 from 215 leaves us with 215.
Include the next digit (9) from the dividend after 215, then repeat: 2159 / 859

Advancing to step 4:
When dividing 2159 by 859, we get 2 with a remainder of 441.
The next digit of our result is 2. 
Result so far: 2.0
Subtract 1718 from 2159 to get 441.
Bring next digit (1) of the dividend behind the 441 and repeat the process: 4411 / 859

Moving on to step 5:
859 goes into 4411 5 times with a remainder of 116.
Write down 5 as next digit of the result. 
Result so far: 25.0
If we take 4295 away from 4411, we end up with 116.
Grab the next digit (8) from the dividend, add it to 116, then carry on: 1168 / 859

Let's proceed to step 6:
859 can be fit into 1168 1 times, resulting in a remainder of 309.
Put 1 as the next digit of the answer. 
Result so far: 251.0
Subtracting 859 from 1168 leaves us with 309.
Append the next digit (2) from the dividend to 309 and continue with: 3092 / 859

Going ahead to step 7:
859 can be fit into 3092 3 times, resulting in a remainder of 515.
Write down 3 as next digit of the result. 
Result so far: 2513.0
If we subtract 2577 from 3092, we get 515.
Bring next digit (3) of the dividend behind the 515 and repeat the process: 5153 / 859

Advancing to step 8:
When dividing 5153 by 859, we get 5 with a remainder of 858.
Write down 5 as next digit of the result. 
Result so far: 25135.0
If we subtract 4295 from 5153, we get 858.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8580, and continue the process.

Moving on to step 9:
When dividing 8580 by 859, we get 9 with a remainder of 849.
The next digit of our result is 9. 
Result so far: 25135.9
If we subtract 7731 from 8580, we get 849.
Since there are no more digits in the dividend, we add a zero to the remainder making it 8490, and continue the process.

Going ahead to step 10:
859 goes into 8490 9 times with a remainder of 759.
Record the quotient 9 as the next digit in the result. 
Result so far: 25135.99
If we take 7731 away from 8490, we end up with 759.
Since there are no more digits in the dividend, we add a zero to the remainder making it 7590, and continue the process.

Our division results in 25135.99 with a remaining 0.759.