21939 ÷ 5 = 4387 R4
Let's divide 21939 by 5.

Step 1:
5 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 / 5

Step 2:
5 goes into 21 4 times with a remainder of 1.
Write down 4 as next digit of of the result. 
Result so far: 4
Subtract 20 from 21 to get 1.
Bring next digit (9) of the dividend behind the 1 and repeat the process: 19 / 5

Step 3:
5 goes into 19 3 times with a remainder of 4.
Write down 3 as next digit of of the result. 
Result so far: 43
Subtract 15 from 19 to get 4.
Bring next digit (3) of the dividend behind the 4 and repeat the process: 43 / 5

Step 4:
5 goes into 43 8 times with a remainder of 3.
Write down 8 as next digit of of the result. 
Result so far: 438
Subtract 40 from 43 to get 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 5

Step 5:
5 goes into 39 7 times with a remainder of 4.
Write down 7 as next digit of of the result. 
Result so far: 4387
Subtract 35 from 39 to get 4.

The final result is 4387 with a remainder of 4.