21864 ÷ 6 = 3644 R0
Let's divide 21864 by 6.

Step 1:
6 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 / 6

Step 2:
6 goes into 21 3 times with a remainder of 3.
Write down 3 as next digit of of the result. 
Result so far: 3
Subtract 18 from 21 to get 3.
Bring next digit (8) of the dividend behind the 3 and repeat the process: 38 / 6

Step 3:
6 goes into 38 6 times with a remainder of 2.
Write down 6 as next digit of of the result. 
Result so far: 36
Subtract 36 from 38 to get 2.
Bring next digit (6) of the dividend behind the 2 and repeat the process: 26 / 6

Step 4:
6 goes into 26 4 times with a remainder of 2.
Write down 4 as next digit of of the result. 
Result so far: 364
Subtract 24 from 26 to get 2.
Bring next digit (4) of the dividend behind the 2 and repeat the process: 24 / 6

Step 5:
6 goes into 24 4 times with a remainder of 0.
Write down 4 as next digit of of the result. 
Result so far: 3644
Subtract 24 from 24 to get 0.

The final result is 3644 with a remainder of 0.