256 has 9 divisors (see below), whose sum is σ = 511. Its totient is φ = 128.
The previous prime is 251. The next prime is 257. The reversal of 256 is 652.
Subtracting from 256 its sum of digits (13), we obtain a 5-th power (243 = 35).
Subtracting from 256 its product of digits (60), we obtain a square (196 = 142).
256 = T15 + T16.
The square root of 256 is 16.
It is a perfect power (a square, a biquadrate, a 8-th power), and thus also a powerful number.
It is a Jordan-Polya number, since it can be written as (2!)8.
256 is nontrivially palindromic in base 15.
256 is an esthetic number in base 15, because in such base its adjacent digits differ by 1.
256 is an undulating number in base 15.
Its product of digits (60) is a multiple of the sum of its prime divisors (2).
It is an enlightened number because it begins with the concatenation of its prime factors (2).
It is a plaindrome in base 10, base 13 and base 14.
It is a nialpdrome in base 2, base 4, base 8 and base 16.
It is not an unprimeable number, because it can be changed into a prime (251) by changing a digit.
In principle, a polygon with 256 sides can be constructed with ruler and compass.
It is an impolite number, since it cannot be written as a nontrivial sum of consecutive naturals.
256 is the 16-th square number.
256 is a deficient number, since it is larger than the sum of its proper divisors (255).
256 is an frugal number, since it uses more digits than its factorization.
256 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 16 (or 2 counting only the distinct ones).
The product of its digits is 60, while the sum is 13.
The cubic root of 256 is about 6.3496042079.
The spelling of 256 in words is "two hundred fifty-six", and thus it is an aban number.