M31

• 2,147,483,647
• HMS Cattistock (M31)
• Hume Highway
• M-31 (Michigan highway)
• M3 Lee
• M31 (Cape Town)
• M31 (Durban)
• M31 (Johannesburg)
• M31 (New York City bus)
• M31 (Pretoria)
• M31 (missile)
• M31 HEAT rifle grenade
• M31 motorway
• M31 motorway (Hungary)
• MGR-1 Honest John
• Messier 31
• Remington Arms
• Remington Model 31
• Samsung Galaxy M31
• Stephen Wright (writer)
• Suomi M-31 SMG