15221 ÷ 4 = 3805 R1
Alright, let's work through the division of 15221 by 4 step by step.

Step 1:
4 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of of the result. 
Result so far: 0
Subtract 0 from 1 to get 1.
Bring next digit (5) of the dividend behind the 1 and repeat the process: 15 / 4

Step 2:
4 goes into 15 3 times with a remainder of 3.
Write down 3 as next digit of of the result. 
Result so far: 3
Subtract 12 from 15 to get 3.
Bring next digit (2) of the dividend behind the 3 and repeat the process: 32 / 4

Step 3:
4 goes into 32 8 times with a remainder of 0.
Write down 8 as next digit of of the result. 
Result so far: 38
Subtract 32 from 32 to get 0.
Bring next digit (2) of the dividend behind the 0 and repeat the process: 2 / 4

Step 4:
4 goes into 2 0 times with a remainder of 2.
Write down 0 as next digit of of the result. 
Result so far: 380
Subtract 0 from 2 to get 2.
Bring next digit (1) of the dividend behind the 2 and repeat the process: 21 / 4

Step 5:
4 goes into 21 5 times with a remainder of 1.
Write down 5 as next digit of of the result. 
Result so far: 3805
Subtract 20 from 21 to get 1.

The final result is 3805 with a remainder of 1.