Fatto generale: 7557 is a number for which we're missing a fact (submit one to numbersapi at google mail!).
Fatto matematico: 7557 is a palindrome that is the sum of the first 37 palindromes.
Trivia: 7557 is an uninteresting number.
Data storica: September 8th is the day in 1380 that Battle of Kulikovo – Russian forces defeat a mixed army of Tatars and Mongols, stopping their advance.