• 678 can be written using four 4's:
678 is nontrivially palindromic in base 15.
678 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.
678 is an esthetic number in base 10 and base 11, because in such bases its adjacent digits differ by 1.
It is a sphenic number, since it is the product of 3 distinct primes.
678 is an admirable number.
It is an alternating number because its digits alternate between even and odd.
678 is an undulating number in base 15.
It is a straight-line number, since its digits are in arithmetic progression.
It is a plaindrome in base 8, base 10, base 11 and base 14.
It is a nialpdrome in base 9.
It is a congruent number.
678 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.
It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.
678 is a wasteful number, since it uses less digits than its factorization.
678 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 118.
The square root of 678 is about 26.0384331326. The cubic root of 678 is about 8.7850296436.