In the natural number 1-20, which number is even and prime

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• 1. If natural numbers n + 3 and N + 7 are prime numbers, find the remainder of N divided by 6
• 2. Is the value of F (n) = N2 + N + 41 prime when n = 1,2,3
• 3. There are four natural numbers less than 10, and their product is 1080. It is known that only one of the four numbers is prime, and this prime is ()
• 4. In the natural numbers from 10 to 20, 15 is both odd and composite. What is the form of the product of several prime numbers?
• 5. In the natural numbers within 10, the two numbers that are prime numbers and coprime numbers can be prime numbers
• 6. "The product of any two adjacent natural numbers plus 41 is prime." is that right? If not, give a counterexample
• 7. Two adjacent natural numbers must be coprime numbers______ (judge right or wrong)
• 8. If two adjacent natural numbers are prime numbers, what are the two numbers? What is the reciprocal of their product
• 9. Two adjacent natural numbers are prime numbers______ And______ All of them are combined______ And______ ．
• 10. A natural number can be decomposed into the product of three prime factors. If the sum of the squares of the three prime factors is 39630, how to find the natural number? What are the numbers with 6 divisors within 100?
• 11. 1. How many primes are there at most among the 20 consecutive natural numbers?
• 12. In two continuous natural numbers less than 10, () and () are both composite numbers and coprime numbers. If the least common multiple of these two numbers is decomposed, the prime factor is ()
• 13. Two numbers are compound numbers and coprime numbers. Their least common multiple is 120. The greatest common divisor of these two numbers is______ Where the smaller sum is______ ．
• 14. There are two natural numbers, even if their coprime numbers are composite numbers. If the least common multiple of these two numbers is 72, what are the two fractions
• 15. () and () are prime numbers and composite numbers. They are coprime RT
• 16. Is a prime number and a composite number necessarily coprime
• 17. Write two coprime numbers that meet the requirements. (1) both are prime numbers () (2) both are composite numbers () (3) both are odd numbers () (4) a prime number and a composite number A cuboid is 8 cm long, 6 cm wide and 5 cm high. Its bottom area is () square cm, its surface area is () square cm and its volume is () cubic cm
• 18. Write a prime number that is coprime with 6. Write a composite number that is coprime with 6
• 19. The sum of all prime numbers within 10 is______ Is a prime and even number______ ．
• 20. I am a prime number, my one digit and ten digit are two adjacent composite numbers in the natural number, I am ()