Both the SLDPRT and PRT formats typically contain CAD data of some part of component, so it is likely one can be converted to each other, provided you find a software that supports both. Solidworks is probably your best choice here.
Convert SolidWorks CAD part to CAD 3D part or component.
We have found 2 software records in our database eligible for .sldprt to .prt file format conversion.
Microsoft Windows software - convert sldprt to prt on Windows
A CAD converter with huge format support
Convert from sldprt file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned sldprt to prt. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A 2D and 3D CAD construction software