python - How to store an integer leaded by zeros in django -

I'm trying to store a number in the widget that looks like this:

 My problem is that if I type it inside an integer field then it gets converted to "1" without leading zero. I have also tried with a single result with the same result, how can I store the leading zero while using extreme farming? (I need to manipulate that number in an integer) 
 

It is not stored with leading zero Please. Instead, format it on output:

  (see: value = 1) {{value | Stringformat: "04d"}} Displays as # 0001