I think the title says it all.

Also, would the number of paper (after submission to easyChair e.g. paper 10) indicates the number of papers that have been submitted?

I've been in the situation where that has happened. Shortly after I completed my PhD (which would have been a good time for me to present), my supervisors were organising the conference (to be held up in Newcastle) and due to location (it wasn't down south) it only attracted interest from a total of ~30 attendees including presenters. It may has well have been in Pyongyang in North Korea for the interest shown.

It was relocated to IOM3 in London so people didn't have to travel beyond London, but by then the damage was done and the conference was 'postponed' and never resurrected.

We'd put in a lot of work (including a paper from me for presentation and proceedings - colleagues similarly) so it was annoying when it finally folded. That said, when that happens, papers can easily be submitted to other conferences and thus the work does not necessarily go to waste.

Ian (Mackem_Beefy)

The deadline of conference could be extended as many as three times until there are more people. It is possible that many prefer to submit their proposal on the last day or last hour; they continue to revise the abstracts again and again.

One of the conference papers that i have recently submitted was assigned the number: 642; but they still extend the deadline two more times.

Based on my limited experience, a “reliable conference” may have the following characteristics:
1. The invited speaker is an editor of journal or someone prominent.
2. There is best paper award, excellent paper award or equivalent…
3. The venue is confirmed. (If the organiser is not sure of the venue, it could be the uncertainty in sufficient number of participants? The organiser has not booked the venue just in case the conference will be folded?)