21089 ÷ 8 = 2636 R1
Let's divide 21089 by 8.

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 (0) of the dividend behind the 5 and repeat the process: 50 / 8

Step 3:
8 goes into 50 6 times with a remainder of 2.
Write down 6 as next digit of of the result. 
Result so far: 26
Subtract 48 from 50 to get 2.
Bring next digit (8) of the dividend behind the 2 and repeat the process: 28 / 8

Step 4:
8 goes into 28 3 times with a remainder of 4.
Write down 3 as next digit of of the result. 
Result so far: 263
Subtract 24 from 28 to get 4.
Bring next digit (9) of the dividend behind the 4 and repeat the process: 49 / 8

Step 5:
8 goes into 49 6 times with a remainder of 1.
Write down 6 as next digit of of the result. 
Result so far: 2636
Subtract 48 from 49 to get 1.

The final result is 2636 with a remainder of 1.