ESI Applicability - if the organisation has 40 employees and none of them are under Rs. 21,000/- except only 4 employees

It is clear that minimum 10 employees are required to register an establishment under ESI in Delhi (shops and establishment) but my question is
a) if the organisation has 40 employees and none of them are under Rs. 21,000/- except only 4 employees who are getting Rs. 15,500/- is it compulsory to register company under ESIC.
b) or till then company will not have 10 employees under Rs. 21,000/- will not be able to take ESI number.
Please clearly urgently.

The company will have to take ESIC registration as number of employees is more than 10/20 as the case may be.