The sum of the first 53 primes is 5830, which is divisible by 53, a property shared by few other numbers.
53 written in hexadecimal is 35, that is, the same characters used in the decimal representation, but reversed. At least four multiples of 53 share this property: 371 = 17316, 5141 = 141516, 99481 =1849916, and 8520280 = 82025816.
53 cannot be expressed as the sum of any integer and its base-10 digits, making 53 a self number.
53 is the smallest prime number that does not divide the order of any sporadic group.
53-TET (53 tone, equal temperament) is a musical temperament that has a fifth that is closer to pure than our current system.
53 More Things To Do In Zero Gravity is a book mentioned in The Hitchhiker's Guide to the Galaxy. It should be noted that 53 is an increment of 42, a number that is frequently referred to in the Hitchhiker series as the meaning of life.