555

Do you want to focus on math, electronics (555 timer), or something else with the number 555? Here are quick math facts you can use for exams:

• Factorization: 555 = 3 × 5 × 37
• Divisors: 1, 3, 5, 15, 37, 111, 185, 555
• Number of divisors: 8
• Sum of divisors σ(555) = 912; sum of proper divisors = 912 − 555 = 357
• Harshad number? Yes, since 5+5+5 = 15 and 555 ÷ 15 = 37
• Binary: 555 = 1000101011₂
• Base-9: 555 = 676₉
• Roman numeral: 555 = DLV

If you meant something else (e.g., 555 timer IC, Roman numerals, or base conversions), tell me which area and I’ll tailor it. Would you like a couple of exam-style practice questions as well?