116991 has 16 divisors (see below), whose sum is σ = 198400. Its totient is φ = 66744.

The previous prime is 116989. The next prime is 116993. The reversal of 116991 is 199611.

It is an interprime number because it is at equal distance from previous prime (116989) and next prime (116993).

It is not a de Polignac number, because 116991 - 2¹ = 116989 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Duffinian number.

116991 is a lucky 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 116991.

It is not an unprimeable number, because it can be changed into a prime (116993) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 121 + ... + 498.

It is an arithmetic number, because the mean of its divisors is an integer number (12400).

2¹¹⁶⁹⁹¹ is an apocalyptic number.

116991 is a deficient number, since it is larger than the sum of its proper divisors (81409).

116991 is an equidigital number, since it uses as much as digits as its factorization.

116991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 635 (or 629 counting only the distinct ones).

The product of its digits is 486, while the sum is 27.

The square root of 116991 is about 342.0394714064. The cubic root of 116991 is about 48.9084783372.

Subtracting from 116991 its sum of digits (27), we obtain a square (116964 = 342²).

The spelling of 116991 in words is "one hundred sixteen thousand, nine hundred ninety-one".