Numbers / 25

The Number 25

25 is composite: factorization 5^2. That gives 25 exactly 3 divisors: 1, 5, 25. 25's proper divisors total just 6, 19 short of 25, the deficient case most of 25's neighbors share too. 25 is also a perfect square, since 5² = 25. 25 has a digit sum of 7; for 25, the digital root works out to 7. 25: 5 all divide 25 evenly, out of 2-12. 25 is 11001 in binary and 19 in hex; as a Roman numeral it's XXV.