857 has 2 divisors, whose sum is σ = 858.
Its totient is φ = 856.
The previous prime is 853. The next prime is 859. The reversal of 857 is 758.
857 is nontrivially palindromic in base 12.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 841 + 16 = 29^2 + 4^2
It is a cyclic number.
It is not a de Polignac number, because 857 - 22 = 853 is a prime.
Together with 859, it forms a pair of twin primes.
It is a Chen prime.
857 is an undulating number in base 12.
It is a plaindrome in base 7 and base 16.
It is not a weakly prime, because it can be changed into another prime (853) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 428 + 429.
It is an arithmetic number, because the mean of its divisors is an integer number (429).
2857 is an apocalyptic number.
It is an amenable number.
857 is a deficient number, since it is larger than the sum of its proper divisors (1).
857 is an equidigital number, since it uses as much as digits as its factorization.
857 is an evil number, because the sum of its binary digits is even.
The product of its digits is 280, while the sum is 20.
The square root of 857 is about 29.2745623366.
The cubic root of 857 is about 9.4986147565.
Subtracting from 857 its reverse (758), we obtain a palindrome (99).
It can be divided in two parts, 85 and 7, that multiplied together give a palindrome (595).
The spelling of 857 in words is "eight hundred fifty-seven", and thus it is an aban number and an oban number.