Subtracting 13981 from its reverse (18931), we obtain a triangular number (4950 = T99).
It is a sphenic number, since it is the product of 3 distinct primes.
It is a 3-Lehmer number, since φ(13981) divides (13981-1)3.
It is a cyclic number.
It is a deceptive number, since it divides R13980.
It is a Duffinian number.
It is a plaindrome in base 16.
It is a nialpdrome in base 7, base 12 and base 15.
It is a zygodrome in base 7.
It is a congruent number.
It is a Poulet number, since it divides 213980-1.
213981 is an apocalyptic number.
13981 is a gapful number since it is divisible by the number (11) formed by its first and last digit.
It is an amenable number.
13981 is a wasteful number, since it uses less digits than its factorization.
13981 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 83.
The square root of 13981 is about 118.2412787482. The cubic root of 13981 is about 24.0905146812.
The spelling of 13981 in words is "thirteen thousand, nine hundred eighty-one".