555

Not sure what you want about 555. Here are a few quick math facts you might find useful for exams:

• Prime factorization: 555 = 3 × 5 × 37
• Divisors: 1, 3, 5, 15, 37, 111, 185, 555
• Sum of divisors: σ(555) = (1+3)(1+5)(1+37) = 4 × 6 × 38 = 912
  • Sum of proper divisors: 912 − 555 = 357
  • Since 357 < 555, 555 is a deficient number
• Divisibility:
  • Divisible by 3 (digit sum 5+5+5 = 15)
  • Divisible by 5 (ends in 5)
  • Not divisible by 7, 11, etc. (e.g., 555 mod 7 = 2, mod 11 = 5)
• Representations:
  • Binary: 555 = 1000101011₂
  • Base-3: 555 = 202120₃

If you’re studying a specific topic (factorization, divisibility tests, number theory, or a problem type), tell me and I’ll tailor a short worked example or practice question using 555.