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This question is about "Which number neither prime nor composite" Here we have to revised again Prime Number and Composite Number
A number is greater than 1 is called a prime number, if it has only two factors, 1 and the number itself i.e 2, 3, 5, 7, 11 ... also notice that prime number are start form 2.
"A number that can be divided exactly by numbers other than 1 or itself is called a composite number" i.e 4, 6, 8, 9, 10... notice that 1 is not included in composite number and 2, 3 are in prime number list therefore composite number are starting from 4.
1 has only one positive divisor that is itself. therefore 1 is not a prime number.
1 cannot be written as a product of two factors, so 1 is also not composite. 1 is also have a unique property that 1 is a number whose reciprocal is also itself which is also a whole number. Anyway 1 is neither prime nor composite number.
29 has only two divisor 1 and 29 itself. Therefore 29 is a prime number.
39 has four divisor 1, 3, 13 and 39. Therefore 39 is a composite number.
Therefore 29 is prime nubmer and 39 is composite. 1 is neithe prime nor composite number. So final answer is 1.