Which microcontroller does the Anycubic i3 Mega / Mega-S use?

The Anycubic i3 Mega (-S) stock mainboard uses the Atmega2560 microcontroller which has the following properties:

• Architecture: AVR
• Manufacturer: Microchip (who bought Atmel)
• Flash: 256kb
• RAM: 4kb
• Stock firmware: Modified Marlin