Adding to 681 its sum of digits (15), we get a palindrome (696).
Subtracting from 681 its sum of digits (15), we obtain a palindrome (666).
Adding to 681 its product of digits (48), we get a 6-th power (729 = 36).
681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
It is a cyclic number.
It is a D-number.
It is a plaindrome in base 11, base 12 and base 14.
It is a nialpdrome in base 4.
It is a self number, because there is not a number n which added to its sum of digits gives 681.
681 is the 17-th centered pentagonal number.
It is an amenable number.
681 is a wasteful number, since it uses less digits than its factorization.
681 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 230.
The square root of 681 is about 26.0959767014. The cubic root of 681 is about 8.7979678503.
The spelling of 681 in words is "six hundred eighty-one", and thus it is an aban number.