143

143 is a special number. If a hypothetical person is going along a number line, marking each number that is divisible by 2, 3, and so on up to 10, 143 is the first non-prime number that they will not stick a number on.

Not Divisible By

• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10

Divisible By

• 1
• 11
• 13
• 143 (itself)

Since the hypothetical person is not sticking 1 on any numbers except 1 and 10 is the highest number they are sticking on, 143 is the first non-prime number without any numbers on it because of the factors 11 and 13.