LV

According to Wikipedia, fifty-five is the natural number following fifty-four and preceding fifty-six. It is also the atomic number of caesium, the tenth Fibonacci number, and the sum of the numbers 1 through 10. It is a square pyramidal number, a centered nonagonal number, and a semiprime number. Between 1974 and 1988, it was the maximum highway speed limit in the United States. It is a magnitude 7.9 barred spiral galaxy in the constellation Sculptor. It is the Autoroute de l'énergie in central Québec and an interstate highway between Chicago and New Orleans. It is the direct-dial calling code for the South American nation of Brazil.

Fifty-five is also my age for the next three hundred and sixty-five days.