78921 ÷ 4 = 19730 R1
Alright, let's work through the division of 78921 by 4 step by step.

Step 1:
4 goes into 7 1 times with a remainder of 3.
Write down 1 as next digit of of the result. 
Result so far: 1
Subtract 4 from 7 to get 3.
Bring next digit (8) of the dividend behind the 3 and repeat the process: 38 / 4

Step 2:
4 goes into 38 9 times with a remainder of 2.
Write down 9 as next digit of of the result. 
Result so far: 19
Subtract 36 from 38 to get 2.
Bring next digit (9) of the dividend behind the 2 and repeat the process: 29 / 4

Step 3:
4 goes into 29 7 times with a remainder of 1.
Write down 7 as next digit of of the result. 
Result so far: 197
Subtract 28 from 29 to get 1.
Bring next digit (2) of the dividend behind the 1 and repeat the process: 12 / 4

Step 4:
4 goes into 12 3 times with a remainder of 0.
Write down 3 as next digit of of the result. 
Result so far: 1973
Subtract 12 from 12 to get 0.
Bring next digit (1) of the dividend behind the 0 and repeat the process: 1 / 4

Step 5:
4 goes into 1 0 times with a remainder of 1.
Write down 0 as next digit of of the result. 
Result so far: 19730
Subtract 0 from 1 to get 1.

The final result is 19730 with a remainder of 1.