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).
To take your question literally, the largest number 'in the world' would have to be the largest number that can be represented on Earth, despite it always being possible to simply add one to any largest number.