And, to be fair, it can't be answered - with any clarity - in such a forum. It would be entirely inappropriate to discuss your specific organization and tell you what might be the number of auditor days. If it were as simple, ANAB could publish the table and you'd already know.
Since the number of days, drives the cost, are you looking for the lowest cost CB? If you are good luck with your search! The few CB's that sell on price alone are normally those whose clients post about here taking 6 months to issue a certificate!
Hemanta, I strongly agree with what is said here - all my experience matches and supports it.
Going for the absolutely cheapest and lowest cost CB has
never in my considerable experience been a good 'strategy'. Ever. In fact, very far from it.
On those (fortunately very few) occasions when I've had the unfortunate experience of being present at an audit done by a 'cheap-as-chips-and-lower-price-than-anyone' CB, it's been a horrible experience all around, not least for the poor clients on whom it was inflicted.
These icons probably sum it up:

:truce:
Valuable? No, not for them.
Lowest cost CB?
Well, if you
like beating your head against brick walls, and if you
like organising your system in whatever way the auditor insists that you should have it to suit them and make it easy and quick to audit and you don't expect to get anything from it except a lot of frustration but a Certificate... go right ahead. But don't expect to get the benefits of a quality system either.
PS: Recent re-audits and certification audits for my clients took no 'extra' time at all. But that was with competent auditors from reputable CBs.