57 (number)

57 was a number.

When the Twelfth Doctor asked Clara Oswald to pick a two-digit number, she chose 57. He then asked the crew of the crew to look at the first word of page 57 of the book they were holding, as part of the Helman-Ziegler test. (TV: Last Christmas)

In an alternate timeline where River Song refused to kill the Eleventh Doctor on 22 April 2011 at 5:02, the time kept alternating between 57 and 58 seconds past the minute. (TV: The Wedding of River Song)