Numbers / 3

The Number 3

3 is prime: only 1 and 3 divide it evenly; the next prime after 3 is 5. 3's proper divisors total just 1, 2 short of 3, the deficient case most of 3's neighbors share too. 3 also carries: the 2nd triangular number, the sum of 1 through 2; and a Fibonacci number, since 2 + 1 = 3. 3 has a digit sum of 3; for 3, the digital root works out to 3. 3 shares no factor with 2-12; 3's own divisors start beyond that range. 3 is 11 in binary and 3 in hex; as a Roman numeral it's III.