The sum of the product of two natural numbers plus 11 is a composite number. What is the minimum sum of these two natural numbers? I don't understand it=

Natural numbers a, B, AB + 11 are composite numbers (composite numbers: in natural numbers greater than 1, numbers that can be divisible by numbers other than 1 and itself, such as 4, 6, 9), then what is the minimum of a + B?
Since AB + 11 is a composite number and a and B are natural numbers, AB + 11 can take 12, 14, 15, 16
When AB + 11 = 12, a = b = 1, then a + B = 2 is the smallest

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