2391 has 4 divisors (see below), whose sum is σ = 3192.
Its totient is φ = 1592.
The previous prime is 2389. The next prime is 2393. The reversal of 2391 is 1932.
It is a semiprime because it is the product of two primes.
It is an interprime number because it is at equal distance from previous prime (2389) and next prime (2393).
It is a cyclic number.
It is not a de Polignac number, because 2391 - 21 = 2389 is a prime.
It is a D-number.
It is a plaindrome in base 13.
It is a nialpdrome in base 7 and base 15.
It is a self number, because there is not a number n which added to its sum of digits gives 2391.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (2393) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (7) of ones.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 396 + ... + 401.
It is an arithmetic number, because the mean of its divisors is an integer number (798).
2391 is a deficient number, since it is larger than the sum of its proper divisors (801).
2391 is an equidigital number, since it uses as much as digits as its factorization.
2391 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 800.
The product of its digits is 54, while the sum is 15.
The square root of 2391 is about 48.8978527136.
The cubic root of 2391 is about 13.3719022144.
It can be divided in two parts, 2 and 391, that added together give a palindrome (393).
The spelling of 2391 in words is "two thousand, three hundred ninety-one".