You can't have leading zeroes when parsing to an Integer, because leading zeroes have no mathematical value.
Your best bet would be to keep it as a String if you need the zeroes
An integer doesn’t contain leading zeros, as leading zeros imply a string. You can replace all non-numeric characters instead if you’re just trying to ‘get all numbers contained in a string’.
replaceAll($String, ‘([^0-9])’, ‘’) should do what you’re trying to accomplish.
This is a very tricky one because integers/ numbers just don't start with a 0 otherwise what number will it actually be?
You will have to keep it as a string in order to keep the zeros in the beginning.