Hecho general: 28873 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Hecho matemático: 28873 is a boring number.
Trivia: 28873 is a boring number.
Fecha histórica: January 18th is the day in 1915 that Japan issues the "Twenty-One Demands" to the Republic of China in a bid to increase its power in East Asia.