The OpenFOAM binary executables are located in the path $WM_PROJECT_DIR/platforms
You can jump to the OpenFOAM platforms directory e.g using system variable $WM_PROJECT_DIR/platforms: # cd $WM_PROJECT_DIR/platforms
This directory contains the binaries generated when compiling the applications directory (after compilation the binaries will be located in the directory e.g.: $WM_PROJECT_DIR/platforms/linux64GccDPOpt/bin) and the libraries generated by compiling the source code in the src directory (after compilation, the libraries will be located in the directory $WM_PROJECT_DIR/platforms/ linux64GccDPOpt/lib).
If you have installed OpenFOAM following the default instructions, you compiled the 64-bit version, using the gcc compiler, with double precision, and optimized version. This is reflected in the name of the directory linux64GccDPOpt.
OpenFOAM 32-bit is also possible to compile. The simulation is nearly two times faster. One has to be very careful about the results. Some cases results are same as 64-bit, but some cases are different or even totally wrong.