Undo a mathematical conversion done inside a black box

Hi and sorry if I posted in the wrong place,

I have a three values Red Green and Blue that are between 0 and 255 e.g.

R:28, G:113, B:244

These three values can then be converted into a Hexadecimal value e.g.

1C71f4

I then have a program that takes the hexadecimal value and converts it to this number:

1005942558

My problem is that I want to convert the final number back into its corresponding hexadecimal value. As I have no idea how this number was converted is there any way of being able to do this?

Thanks in advance for any help I get on this.