Hi manojkumaru!
Yes, there is still people using the N900, and some intensively, from what I could read, even for tasks much easier doable with other machines
How much? I can't say.
There is a thread How many of you still use N900 as main phone? but the last post is from 2015.
We could wake it up or make a new one for 2020!
By my side, I can say 4 people with 5 N900.
Cheers and welcome back!