unfortunately none.  your 3650 has intel 100 series chipset which does not support intel 8th gen or higher gen cpu which are eligible for Windows 11.  on the other hand you may install Win 11 using some software tricks so that your ineligible cpu can still run win 11.  you just would not get update or support from Microsoft.
My Inspiron 3650 has an intel  i3-6100 CPU @ 3.7ghz CPU that is not compatible with Windows 11. What Windows 11 compatible CPUs are also compatible with my Inspiron?
Dell Inspiron 3650 - CPU for Windows 11