• 255 can be written using four 4's:
255 is nontrivially palindromic in base 2, base 4, base 9, base 11 and base 16.
255 is an esthetic number in base 11, because in such base its adjacent digits differ by 1.
It is a sphenic number, since it is the product of 3 distinct primes.
It is a 7-Lehmer number, since φ(255) divides (255-1)7.
It is a cyclic number.
255 is an undulating number in base 9 and base 11.
255 is a nontrivial repdigit in base 2, base 4 and base 16.
It is a plaindrome in base 2, base 4, base 8, base 10, base 13 and base 16.
It is a nialpdrome in base 2, base 4 and base 16.
It is a zygodrome in base 2, base 4 and base 16.
It is a self number, because there is not a number n which added to its sum of digits gives 255.
It is a congruent number.
In principle, a polygon with 255 sides can be constructed with ruler and compass.
255 is a wasteful number, since it uses less digits than its factorization.
255 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 25.
The square root of 255 is about 15.9687194227. The cubic root of 255 is about 6.3413257054.
Subtracting from 255 its sum of digits (12), we obtain a 5-th power (243 = 35).
The spelling of 255 in words is "two hundred fifty-five", and thus it is an aban number.