Meaning of a line in question

#1

i am not able to understand the meaning of following line in question finding cb number
Any number not divisible by the numbers in point 2( Given above) are also CB numbers.
please explain it

#2

Hi Vaibhav,
All numbers which are not divisible by 2,3,5,7,11,13,17,19,23, and 29 are CB numbers.