The two elements that have no symbol letter but only a number are Ununtrium (element 113) and Ununpentium (element 115). These elements were originally synthesized in a laboratory and have not yet been officially named. As a result, they are temporarily designated by their atomic numbers.
Ununtrium (113) has an atomic number of 113, indicating that it has 113 protons in its nucleus. Ununpentium (115) has an atomic number of 115, indicating it has 115 protons.
As for the total number of such elements on Earth and in the universe, it is difficult to provide an exact figure because the discovery and synthesis of new elements is an ongoing process. the last officially named element was Oganesson (element 118). However, scientists continue to search for and synthesize new elements beyond this point in the periodic table. Therefore, the total number of such elements can change as new elements are discovered or synthesized in the future.