11681 has 2 divisors, whose sum is σ = 11682. Its totient is φ = 11680.

The previous prime is 11677. The next prime is 11689. The reversal of 11681 is 18611.

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 not a de Polignac number, because 11681 - 2² = 11677 is a prime.

It is a super-2 number, since 2×11681² = 272891522, which contains 22 as substring.

It is a Chen prime.

It is a nialpdrome in base 5.

It is not a weakly prime, because it can be changed into another prime (11689) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5840 + 5841.

It is an arithmetic number, because the mean of its divisors is an integer number (5841).

2¹¹⁶⁸¹ is an apocalyptic number.

It is an amenable number.

11681 is a deficient number, since it is larger than the sum of its proper divisors (1).

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 product of its digits is 48, while the sum is 17.

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".