() 1. The larger the natural number, the more factors it has.

() 2. The product of multiplication of two prime numbers is still a prime number.

() 3. A composite number must have at least three factors.

() 4. In the natural sequence, all even numbers except 2 are composite numbers.

() 5 factors. 15 is 3 and 5.

() 6. Among the numbers of1-40, 36 is the largest multiple of 4.

() 7. 1 is a factor of 16, and 16 is a multiple of 16.

() A multiple of 8. Eight is only two, four.

() 9. The maximum factor and minimum multiple of a number are itself, that is to say, the maximum factor of a number is equal to it.

Minimum multiple of.

() 10. There is no maximum multiple for any number.

() 1 1. 1 is a factor of all nonzero natural numbers.

() 12. All even numbers are composite numbers.

() 13. Is the product of prime numbers and prime numbers still prime numbers?

() 14. Numbers with 3, 6 and 9 in each position can be divisible by 3.

() 15. The factor of a number is always less than this number.

Unit of () 16. 743 is 3, so 743 is a multiple of 3.

The largest prime number in () 17. 100 is 99.

Fill in the blanks.

1. Among natural numbers within 50, the largest prime number is () and the smallest composite number is ().

2. The smallest number that is both prime and odd is ().

A prime number within 3.20, () plus 2 is still a prime number.

4. If the sum of two prime numbers is equal to 24, it can be ()+(), ()+() or ()+().

5. Among natural numbers, the smallest odd number is (), the smallest even number is (), the smallest prime number is (), and the smallest composite number is ().

6. A prime number has only () factors, namely () and ().

7. A composite number has at least () factors, and () is neither a prime number nor a composite number.

8. Among natural numbers, the one that is both prime and even is ().

9. At 27, 68, 44, 72, 587, 602, 43 1, 800.

Odd numbers are: even numbers are:

10. At 2, 3, 45, 10, 22, 17, 5 1, 9 1, 93, 97.

The prime number is: the composite number is:

Third, choose.

1. In 14 = 2× 7, both 2 and 7 are 14 ().

① prime number ② factor ③ prime factor

2. A basket of apples, two bought one, three bought one, four bought one and five bought one, all of which have just been eaten, and there is no surplus. This basket of apples should have at least ().

① 120，②90，③60，④30。

3. In natural numbers, any multiple of 17 ().

① even numbers; ② Even and odd numbers; ③ odd numbers.

4. The sum of two prime numbers is ().

① Even number ② Odd number ③ Odd number or even number.

5. Natural numbers can be divided into () according to whether they are multiples of 2.

① Odd and even numbers ② Prime numbers and composite numbers ③ Prime numbers, composite numbers, 0 and 1.

6. 1 Yes ().

① Prime number ② Composite number ③ Odd number ④ Even number

By hand. If there is any similarity, it is definitely a coincidence! ! (Not enough to supplement)