The largest digit mentioned is hundred millions (in the first clue),
so it is a 9-digit number. We will fill in the blanks as we go along.
_ _ _, _ _ _, _ _ _
I have 1s in my millions and ones places.
_ _ 1, _ _ _, _ _ 1
I have 3 hundreds.
_ _ 1, _ _ _, 3 _ 1
I have 4 ten thousands.
_ _ 1, _ 4 _, 3 _ 1
The numbers in my hundred thousands and ten millions place is half my ten thousands digit.
Since the ten thousands digit is 4, those two digits are 2's.
_ 2 1, 2 4 _, 3 _ 1
All my other numbers are double my millions digit.
Since the millions digit is 1, all the others are 2's.
2 2 1, 2 4 2, 3 2 1
Edwin