555

Did you mean the number 555? Here are quick facts and a small practice set you can use for exam prep.

Quick facts about 555

• Prime factorization: 555 = 3 × 5 × 37
• Divisors: 1, 3, 5, 15, 37, 111, 185, 555
• Number of divisors: 8
• Sum of all divisors σ(555) = 912; sum of proper divisors = 912 − 555 = 357
• Is 555 deficient, perfect, or abundant? Deficient (357 < 555)
• Euler totient: φ(555) = 288
• Digit sum: 5 + 5 + 5 = 15; digital root = 6
• In Roman numerals: DLV
• Binary: 1000101011₂
• Octal: 1053₈

Practice problems

1. Factor and divisors

• Part a: Confirm the prime factorization: 555 = 3 × 5 × 37.
• Part b: List all divisors and verify there are 8.

2. Sum of divisors and deficiency

• Compute the sum of the proper divisors of 555. Is 555 deficient, perfect, or abundant?

3. Euler’s totient

• Compute φ(555) using the formula φ(n) = n ∏(1 − 1/p) over distinct primes p|n. Check your result.

If you want, I can tailor more problems to a specific topic (e.g., divisors, modular arithmetic, factorization) or generate a timed mini-quiz.