110991 has 4 divisors (see below), whose sum is σ = 147992. Its totient is φ = 73992.

The previous prime is 110989. The next prime is 111029. The reversal of 110991 is 199011.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 199011 = 3 ⋅66337.

It is not a de Polignac number, because 110991 - 2¹ = 110989 is a prime.

It is a D-number.

It is a Duffinian number.

It is a nialpdrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (110921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18496 + ... + 18501.

It is an arithmetic number, because the mean of its divisors is an integer number (36998).

2¹¹⁰⁹⁹¹ is an apocalyptic number.

110991 is a deficient number, since it is larger than the sum of its proper divisors (37001).

110991 is an equidigital number, since it uses as much as digits as its factorization.

110991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37000.

The product of its (nonzero) digits is 81, while the sum is 21.

The square root of 110991 is about 333.1531179503. The cubic root of 110991 is about 48.0576564113.

The spelling of 110991 in words is "one hundred ten thousand, nine hundred ninety-one".