The number two.
None, 53 is a prime number.
How about: 80
2
2 and 10 go into 40 and 50 evenly.
No numbers besides itself and 1 go into it evenly. The most common numbers to check are 2,3,4,5,6,9, and 10. THe rest you can figure out with times tables.
There are no other whole numbers besides ' 1 ' and 19 that go into 19 evenly. That makes 19 a prime number.
Only the number one.
Only the number one.
Least number is 40
30
These numbers go evenly into 20: 1, 2, 4, 5, 10, 20.
10 and 5 can go into 150 evenly.