13981 has 8 divisors (see below), whose sum is σ = 16128. Its totient is φ = 12000.

The previous prime is 13967. The next prime is 13997. The reversal of 13981 is 18931.

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 not a de Polignac number, because 13981 - 2⁹ = 13469 is a prime.

It is a super-2 number, since 2×13981² = 390936722, which contains 22 as substring.

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 not an unprimeable number, because it can be changed into a prime (13901) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 321 + ... + 361.

It is an arithmetic number, because the mean of its divisors is an integer number (2016).

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 deficient number, since it is larger than the sum of its proper divisors (2147).

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 product of its digits is 216, while the sum is 22.

The square root of 13981 is about 118.2412787482. The cubic root of 13981 is about 24.0905146812.

Subtracting 13981 from its reverse (18931), we obtain a triangular number (4950 = T₉₉).

The spelling of 13981 in words is "thirteen thousand, nine hundred eighty-one".