21839 ÷ 6 = 3639 R5
Let's divide 21839 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 (3) of the dividend behind the 2 and repeat the process: 23 / 6

Step 4:
6 goes into 23 3 times with a remainder of 5.
Write down 3 as next digit of of the result. 
Result so far: 363
Subtract 18 from 23 to get 5.
Bring next digit (9) of the dividend behind the 5 and repeat the process: 59 / 6

Step 5:
6 goes into 59 9 times with a remainder of 5.
Write down 9 as next digit of of the result. 
Result so far: 3639
Subtract 54 from 59 to get 5.

The final result is 3639 with a remainder of 5.