It is a happy number.
11681 is digitally balanced in base 2 and base 3, because in such bases it contains all the possibile digits an equal number of times.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 10000 + 1681 = 100^2 + 41^2 .It is also a bemirp because it and its reverse can be mirrored producing other two distinct primes, 18911 and 11981.
It is a cyclic number.
It is a Chen prime.
It is a nialpdrome in base 5.
211681 is an apocalyptic number.
It is an amenable number.
11681 is an equidigital number, since it uses as much as digits as its factorization.
11681 is an odious number, because the sum of its binary digits is odd.
The square root of 11681 is about 108.0786750474. The cubic root of 11681 is about 22.6895913778.
Subtracting from 11681 its sum of digits (17), we obtain a square (11664 = 1082).
The spelling of 11681 in words is "eleven thousand, six hundred eighty-one".