• 53 can be written using four 4's:
53 is an esthetic number in base 8 and base 12, because in such bases its adjacent digits differ by 1.
53 is a truncatable prime.
It is a cyclic number.
It is a Sophie Germain prime.
It is a Chen prime.
It is an Ulam number.
It is a Curzon number.
It is a plaindrome in base 3, base 6, base 9, base 11, base 12, base 14, base 15 and base 16.
It is a nialpdrome in base 4, base 8, base 10 and base 13.
It is a self number, because there is not a number n which added to its sum of digits gives 53.
It is a congruent number.
It is a panconsummate number.
It is a good prime.
It is an amenable number.
53 is an equidigital number, since it uses as much as digits as its factorization.
It is an anagram of its base 16 representation: 53 = (35)16.
53 is an evil number, because the sum of its binary digits is even.
The square root of 53 is about 7.2801098893. The cubic root of 53 is about 3.7562857542.
Adding to 53 its reverse (35), we get a palindrome (88).