• 93 can be written using four 4's:
93 is nontrivially palindromic in base 2 and base 5.
It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 39 = 3 ⋅13.
93 is an idoneal number.
It is a D-number.
It is a Duffinian number.
93 is a lucky number.
93 is a nontrivial repdigit in base 5.
It is a plaindrome in base 5, base 6, base 8, base 9, base 12, base 14 and base 16.
It is a nialpdrome in base 5, base 10, base 11, base 13 and base 15.
It is a zygodrome in base 5.
It is a congruent number.
It is an amenable number.
93 is a wasteful number, since it uses less digits than its factorization.
93 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 34.
The square root of 93 is about 9.6436507610. The cubic root of 93 is about 4.5306548961.
Adding to 93 its sum of digits (12), we get a triangular number (105 = T14).
Subtracting from 93 its sum of digits (12), we obtain a 4-th power (81 = 34).
Adding to 93 its product of digits (27), we get a triangular number (120 = T15).
Subtracting from 93 its product of digits (27), we obtain a palindrome (66).