Numbers / 5

The Number 5

5 is prime: only 1 and 5 divide it evenly; the next prime after 5 is 7. 5's proper divisors total just 1, 4 short of 5, the deficient case most of 5's neighbors share too. 5 is also a Fibonacci number, since 3 + 2 = 5. 5 has a digit sum of 5; for 5, the digital root works out to 5. 5 shares no factor with 2-12; 5's own divisors start beyond that range. 5 is 101 in binary and 5 in hex; as a Roman numeral it's V.