11857 has 4 divisors (see below), whose sum is σ = 12096. Its totient is φ = 11620.

The previous prime is 11839. The next prime is 11863. The reversal of 11857 is 75811.

11857 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 75811 = 47 ⋅1613.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-11857 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a plaindrome in base 11 and base 14.

It is a nialpdrome in base 13.

It is not an unprimeable number, because it can be changed into a prime (11807) 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, 13 + ... + 154.

It is an arithmetic number, because the mean of its divisors is an integer number (3024).

2¹¹⁸⁵⁷ is an apocalyptic number.

It is an amenable number.

11857 is a deficient number, since it is larger than the sum of its proper divisors (239).

11857 is an equidigital number, since it uses as much as digits as its factorization.

11857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 238.

The product of its digits is 280, while the sum is 22.

The square root of 11857 is about 108.8898526034. The cubic root of 11857 is about 22.8029800147.

It can be divided in two parts, 11 and 857, that added together give a palindrome (868).

The spelling of 11857 in words is "eleven thousand, eight hundred fifty-seven".