403536 divided by 21 
We're looking to find how many times 21 goes into 403536.

Moving on to step 1:
If we divide 4 by 21, we get 0 and a remainder of 4.
Put 0 as the next digit of the answer. 
Result so far: 0.0
Subtract 0 from 4 to get 4.
Take the next digit (0) from the dividend and append it to 4, then repeat: 40 / 21

Step 2:
The number 21 fits into 40 1 times, leaving a remainder of 19.
The number 1 becomes the next digit in our result. 
Result so far: 1.0
If we subtract 21 from 40, we get 19.
Fetch the next digit (3) from the dividend, attach it to 19 and continue: 193 / 21

Let's proceed to step 3:
If we divide 193 by 21, we get 9 and a remainder of 4.
Put 9 as the next digit of the answer. 
Result so far: 19.0
The remainder is 4 after subtracting 189 from 193.
Grab the next digit (5) from the dividend, add it to 4, then carry on: 45 / 21

Going ahead to step 4:
The number 21 fits into 45 2 times, leaving a remainder of 3.
Put 2 as the next digit of the answer. 
Result so far: 192.0
Subtract 42 from 45 to get 3.
Fetch the next digit (3) from the dividend, attach it to 3 and continue: 33 / 21

On to step 5:
When dividing 33 by 21, we get 1 with a remainder of 12.
Put 1 as the next digit of the answer. 
Result so far: 1921.0
Subtract 21 from 33 to get 12.
Append the next digit (6) from the dividend to 12 and continue with: 126 / 21

Step 6:
21 can be fit into 126 6 times, resulting in a remainder of 0.
The number 6 becomes the next digit in our result. 
Result so far: 19216.0
If we take 126 away from 126, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Let's proceed to step 7:
21 can be fit into 0 0 times, resulting in a remainder of 0.
Record the quotient 0 as the next digit in the result. 
Result so far: 19216.0
Subtracting 0 from 0 leaves us with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

Going ahead to step 8:
21 can be fit into 0 0 times, resulting in a remainder of 0.
Use 0 as the next digit of our solution. 
Result so far: 19216.0
If we take 0 away from 0, we end up with 0.
Since there are no more digits in the dividend, we add a zero to the remainder making it 0, and continue the process.

In conclusion, the division gives 19216.0 with a balance of 0.0.