Is any math can sort out date from time-milli? (eg:1544901911) It is possible to get time by a initial modulus of 86400 and dividing 3600 (hour) and modulus by 3600 and dividing by 60 (minute) of overal milli. Is it possible to get date from these, I really don't know how it works (just knows that it begined from 1970 Jan 1 onwards). Not using any code language, I am just asking the mathematics behind this.
I have problems making sense of what you wrote. 86400 is the number of seconds in a day. So if you have the time in seconds, and want the time of the day, then modulo 86400 makes sense. As your question starts with time in milliseconds, modulo 86400000 would be more appropriate. But I guess we get the idea either way.
So as I said, extracting the time of the day works as you know the number of seconds in a day. The number of seconds in a year is harder, as you have to deal with leap days. You can have a look at existing standard library implementations, e.g. Python datetime. That starts by taking the time (or rather number of days, i.e. time divided by time per day, whatever the unit) modulo 400 years, since the number of whole days in 400 years is fixed. Then it goes on looking at 100 year cycles, 4 year cycles and years, with case distinctions for leap years, and tables containing information about month lengths, and so on. Yes, this can be done, but it's tedious plus already part of standard libraries for most languages.