I started this thread in the wrong place... In summary, $and(4294967296,1) does not evaluate to a correct value (due to 32-bit operations that are being saturated). I know, not many people use $and/$or/$xor and due to the nature of $not one can't expect them to have some "variable limit" like $calc, but would it be possible to modify this behaviour, and perhaps document the limits/behaviour so it doesn't surprise anyone else?