21239 ÷ 4 = 5309 R3
Let's divide 21239 by 4.

Step 1:
4 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 / 4

Step 2:
4 goes into 21 5 times with a remainder of 1.
Write down 5 as next digit of of the result. 
Result so far: 5
Subtract 20 from 21 to get 1.
Bring next digit (2) of the dividend behind the 1 and repeat the process: 12 / 4

Step 3:
4 goes into 12 3 times with a remainder of 0.
Write down 3 as next digit of of the result. 
Result so far: 53
Subtract 12 from 12 to get 0.
Bring next digit (3) of the dividend behind the 0 and repeat the process: 3 / 4

Step 4:
4 goes into 3 0 times with a remainder of 3.
Write down 0 as next digit of of the result. 
Result so far: 530
Subtract 0 from 3 to get 3.
Bring next digit (9) of the dividend behind the 3 and repeat the process: 39 / 4

Step 5:
4 goes into 39 9 times with a remainder of 3.
Write down 9 as next digit of of the result. 
Result so far: 5309
Subtract 36 from 39 to get 3.

The final result is 5309 with a remainder of 3.