can you tell me how many letter of words should i keep company name and my lucky number?

Shreyas, I personally don't think that it is necessary for you to decide your company name. Instead, you should comply with the regulations for company registration. And you can choose your phone number and company adress based on your lucky numbers.

2, 3 and 7 are your lucky numbers. So you should find a phone number and company address that contain these three numbers. They might flourish your business.