21965 ÷ 4 = 5491 R1
Alright, let's work through the division of 21965 by 4 step by step.

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 (9) of the dividend behind the 1 and repeat the process: 19 / 4

Step 3:
4 goes into 19 4 times with a remainder of 3.
Write down 4 as next digit of of the result. 
Result so far: 54
Subtract 16 from 19 to get 3.
Bring next digit (6) of the dividend behind the 3 and repeat the process: 36 / 4

Step 4:
4 goes into 36 9 times with a remainder of 0.
Write down 9 as next digit of of the result. 
Result so far: 549
Subtract 36 from 36 to get 0.
Bring next digit (5) of the dividend behind the 0 and repeat the process: 5 / 4

Step 5:
4 goes into 5 1 times with a remainder of 1.
Write down 1 as next digit of of the result. 
Result so far: 5491
Subtract 4 from 5 to get 1.

The final result is 5491 with a remainder of 1.