Answer:
It contains 53 protons in it's nucleus, 53 electrons outside of it's nucleus, and the number of neutrons is 74. (Because the sum of the numbers of protons and neutrons equals the mass number, 127, the number of neutrons is 74 (127 − 53 = 74))
(I got the last bit of information from https://chem.libretexts.org/Bookshelves/General_Chemistry/Book%3A_Chemistry_(OpenSTAX)/02%3A_Atoms%2C_Molecules%2C_and_Ions/2.3%3A_Atomic_Structure_and_Symbolism if you want to look more into it)
