Are Android tracking apps legit? I'm wondering if the apps, which claim about tracking a phone number and giving you the exact location of the caller really work. Is this really possible? If so, how? And what's the name for the app that could do this?
Say I have the phone number 1-123-456-7890. The 1 is the country code, 1 is the USA. In the USA phone numbers are split geographly into area codes (123). Area codes are split into central office codes (usually also geographic)(456). The last four numbers (7890) are either randomly assigned, assigned in order, or chosen by the customer from a list of available numbers. With area code and CO code, you can get what state and city they phone number is (or what city it was registered in the case of a cell phone). My Samsung Galaxy S5's OS (Marshmallow) tells me what state the number is from. There are some special area codes such as 800 and 710.
Other countries may have different telephone numbering plans, and even base cost on area codes you are tying to call:

https://en.wikipedia.org/wiki/Telephone_numbering_plan

More info:

https://en.wikipedia.org/wiki/Toll-free_telephone_numbers_in_the_North_American_Numbering_Plan

https://en.wikipedia.org/wiki/Area_code_710

If you are worried about others knowing what state/city you live in you can type *67 before the number you want to call. (ex *671234567890) You will show up as private number. They will not have your number, so unless you tell them your number they can not call you back.

https://en.wikipedia.org/wiki/Vertical_service_code

The only legal way (in the US) to get your location, is to get a warrant and the cell company has to give up your location. The only exception is when you call 911, they will have your location without a warrant.