2091 has 8 divisors (see below), whose sum is σ = 3024.
Its totient is φ = 1280.
The previous prime is 2089. The next prime is 2099. The reversal of 2091 is 1902.
Adding to 2091 its reverse (1902), we get a palindrome (3993).
It can be divided in two parts, 209 and 1, that added together give a triangular number (210 = T20).
It is a happy number.
It is a sphenic number, since it is the product of 3 distinct primes.
It is a 8-Lehmer number, since φ(2091) divides (2091-1)8.
It is a cyclic number.
It is not a de Polignac number, because 2091 - 21 = 2089 is a prime.
It is a nialpdrome in base 14.
It is not an unprimeable number, because it can be changed into a prime (2099) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (5) of ones.
It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31 + ... + 71.
It is an arithmetic number, because the mean of its divisors is an integer number (378).
2091 is a deficient number, since it is larger than the sum of its proper divisors (933).
2091 is a wasteful number, since it uses less digits than its factorization.
2091 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 61.
The product of its (nonzero) digits is 18, while the sum is 12.
The square root of 2091 is about 45.7274534607.
The cubic root of 2091 is about 12.7874714651.
The spelling of 2091 in words is "two thousand, ninety-one".