21815509 ÷ 25 
Let's see how many times 25 fits into 21815509.

Step 1:
25 goes into 2 0 times with a remainder of 2.
Use 0 as the next digit of our solution. 
Result so far: 0.0
Subtract 0 from 2 to get 2.
Append the next digit (1) from the dividend to 2 and continue with: 21 / 25

Moving on to step 2:
25 can be fit into 21 0 times, resulting in a remainder of 21.
The number 0 becomes the next digit in our result. 
Result so far: 0.0
Subtract 0 from 21 to get 21.
Fetch the next digit (8) from the dividend, attach it to 21 and continue: 218 / 25

Let's proceed to step 3:
If we divide 218 by 25, we get 8 and a remainder of 18.
The next digit of our result is 8. 
Result so far: 8.0
The remainder is 18 after subtracting 200 from 218.
Include the next digit (1) from the dividend after 18, then repeat: 181 / 25

Going ahead to step 4:
The number 25 fits into 181 7 times, leaving a remainder of 6.
Write down 7 as next digit of the result. 
Result so far: 87.0
If we subtract 175 from 181, we get 6.
Include the next digit (5) from the dividend after 6, then repeat: 65 / 25

Going ahead to step 5:
The number 25 fits into 65 2 times, leaving a remainder of 15.
Record the quotient 2 as the next digit in the result. 
Result so far: 872.0
The remainder is 15 after subtracting 50 from 65.
Fetch the next digit (5) from the dividend, attach it to 15 and continue: 155 / 25

Let's proceed to step 6:
The number 25 fits into 155 6 times, leaving a remainder of 5.
The number 6 becomes the next digit in our result. 
Result so far: 8726.0
Deduct 150 from 155 and we're left with 5.
Fetch the next digit (0) from the dividend, attach it to 5 and continue: 50 / 25

On to step 7:
When dividing 50 by 25, we get 2 with a remainder of 0.
The number 2 becomes the next digit in our result. 
Result so far: 87262.0
The remainder is 0 after subtracting 50 from 50.
Append the next digit (9) from the dividend to 0 and continue with: 9 / 25

Advancing to step 8:
If we divide 9 by 25, we get 0 and a remainder of 9.
The next digit of our result is 0. 
Result so far: 872620.0
Subtracting 0 from 9 leaves us with 9.
Since there are no more digits in the dividend, we add a zero to the remainder making it 90, and continue the process.

Step 9:
25 goes into 90 3 times with a remainder of 15.
Put 3 as the next digit of the answer. 
Result so far: 872620.3
If we take 75 away from 90, we end up with 15.
Since there are no more digits in the dividend, we add a zero to the remainder making it 150, and continue the process.

Advancing to step 10:
The number 25 fits into 150 6 times, leaving a remainder of 0.
The next digit of our result is 6. 
Result so far: 872620.36
Deduct 150 from 150 and we're left 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.

On to step 11:
If we divide 0 by 25, we get 0 and a remainder of 0.
The number 0 becomes the next digit in our result. 
Result so far: 872620.36
If we subtract 0 from 0, we get 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 12:
The number 25 fits into 0 0 times, leaving a remainder of 0.
Write down 0 as next digit of the result. 
Result so far: 872620.36
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 872620.36 with a balance of 0.0.