See no (in its different meanings) and 1 ("symbol of the numerical unit, the number one"). [Note: It should be clarified that the Spanish abbreviations for "number" are numer . or n . º . See flown . ]
No. 1 , is the abbreviation for number 1 (number one). It refers to that person or thing that precedes the others of its kind in order, time, place, situation, class or hierarchy.