Nitro, Nitroso, Nitrate, and Nitrite Compounds, Organic. Reactive groups are categories of chemicals that typically react in similar ways because they are similar in their chemical structure. Each substance with a chemical datasheet has been assigned to one or more reactive groups, and CAMEO Chemicals uses the reactive group assignments to make its reactivity predictions.
The largest  number that has a commonly-known specific name is a googolplex,  which is a 1 followed by a googol zeros, where googol is 10100 (a 1  followed by 100 zeros).
Judging by the number of covers and recordings of the song, The Beatles' Yesterday is the most popular. It has the Guinness World Record for being recorded the most number of times. Guinness' site says it had been recorded 1600 times from 1965 to January 1, 1986.