Numbers / 857

The Number 857

857 is prime: only 1 and 857 divide it evenly; the next prime after 857 is 859. 857's proper divisors total just 1, 856 short of 857, the deficient case most of 857's neighbors share too. 857 has a digit sum of 20; for 857, the digital root works out to 2. 857 shares no factor with 2-12; 857's own divisors start beyond that range. 857 is 1101011001 in binary and 359 in hex; as a Roman numeral it's DCCCLVII.