I would use a dispatch table like the following. It's a little effort to set it up, but that prevents you from calling unforeseen functions for malicious or erroneous inputs:

my %dispatch = (
    'func1_1' => \&func1_1,
    'func1_2' => \&func1_2,
    'func2_1' => \&func2_1,
);

$dispatch{ 'func' . $number1 . '_' . $number2 }->( @params );
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