Look for a small barcode label on the motherboard. The model usually starts with "D" (e.g., Go to product viewer dialog for this item.
If you are seeing the code on your Intel motherboard, you might be looking for a specific driver to get your system working. However, it is important to clarify that "21 B6 E1 E2" is not a motherboard model number; it is a series of BIOS Post Codes that often appear on the board's diagnostic display during the boot process. intel desktop board 21 b6 e1 e2 driver work