21621 ÷ 8 = 2702 R5
We're going to perform division on 21621 with 8 as the divisor.

Step 1:
8 goes into 2 0 times with a remainder of 2.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 2 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 8

Step 2:
8 goes into 21 2 times with a remainder of 5.
Write down 2 as next digit of of the result. 
Result so far: 2
Subtract 16 from 21 to get 5.
Bring next digit (6) of the dividend behind the 5 and repeat the process: 56 / 8

Step 3:
8 goes into 56 7 times with a remainder of 0.
Write down 7 as next digit of of the result. 
Result so far: 27
Subtract 56 from 56 to get 0.
Bring next digit (2) of the dividend behind the 0 and repeat the process: 2 / 8

Step 4:
8 goes into 2 0 times with a remainder of 2.
Write down 0 as next digit of of the result. 
Result so far: 270
Subtract 0 from 2 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 8

Step 5:
8 goes into 21 2 times with a remainder of 5.
Write down 2 as next digit of of the result. 
Result so far: 2702
Subtract 16 from 21 to get 5.

The final result is 2702 with a remainder of 5.