113991 has 4 divisors (see below), whose sum is σ = 151992. Its totient is φ = 75992.

The previous prime is 113989. The next prime is 114001. The reversal of 113991 is 199311.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 113991 - 2¹ = 113989 is a prime.

It is a D-number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 113991.

It is not an unprimeable number, because it can be changed into a prime (113921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18996 + ... + 19001.

It is an arithmetic number, because the mean of its divisors is an integer number (37998).

2¹¹³⁹⁹¹ is an apocalyptic number.

113991 is a deficient number, since it is larger than the sum of its proper divisors (38001).

113991 is an equidigital number, since it uses as much as digits as its factorization.

113991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38000.

The product of its digits is 243, while the sum is 24.

The square root of 113991 is about 337.6255322099. The cubic root of 113991 is about 48.4867998228.

The spelling of 113991 in words is "one hundred thirteen thousand, nine hundred ninety-one".