$not
From Scriptwiki
Performs a bit-wise NOT comparison against two numbers
$not(number 1, number 2)
Something to Consider
mIRC deals with all numbers as DWORDs (4-byte integers with a max value of 11111111111111111111111111111111 or 4294967295 in decimal). Therefore, when performing a not, take into consideration all of the "0"s that may be before your number.
Examples
$not(4294967294,4294967295)
Binary values of each:
11111111111111111111111111111101 11111111111111111111111111111110
Leaving the bits which are NOT in 4294967294 but are in 4294967295
Returns: 2 (00000000000000000000000000000010)