problematic conversion from int to intptr

string pIDs = Convert.ToString(p.Id);//p.Id is an integer. Will convert to string to retain value.
IntPtr pID = new IntPtr(Convert.ToInt32(pIDs, 16));//This will converted to hexadecimal but the value doesn't change.

Errors:
> An unhandled exception of type 'System.Runtime.InteropServices.COMException' occurred in FrozUn.exe
Exception from HRESULT: 0xC000000
> I wanted 0x8456 but in the end I got 0x0000000000008456 (intPtr) from 8456 (integer)