13921 has 2 divisors, whose sum is σ = 13922.
Its totient is φ = 13920.
The previous prime is 13913. The next prime is 13931. The reversal of 13921 is 12931.
Subtracting from 13921 its reverse (12931), we obtain a triangular number (990 = T44).
13921 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., 12321 + 1600 = 111^2 + 40^2
It is a cyclic number.
It is not a de Polignac number, because 13921 - 23 = 13913 is a prime.
It is a junction number, because it is equal to n+sod(n) for n = 13895 and 13904.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (13901) 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, 6960 + 6961.
It is an arithmetic number, because the mean of its divisors is an integer number (6961).
213921 is an apocalyptic number.
It is an amenable number.
13921 is a deficient number, since it is larger than the sum of its proper divisors (1).
13921 is an equidigital number, since it uses as much as digits as its factorization.
13921 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 54, while the sum is 16.
The square root of 13921 is about 117.9872874508.
The cubic root of 13921 is about 24.0560034747.
The spelling of 13921 in words is "thirteen thousand, nine hundred twenty-one".