171
CLXXI
10101011
The number 171 — factors and divisors
Deficient
171 = 3² × 19. It has 6 divisors, adding up to 260.
Its divisors, itself excluded, add up to less than the number.
Families it belongs to
Triangular
The running total of 1, 2, 3 … — the dots stack into a triangle.
Laid out as dots
It fits as 9 × 19. The more divisors, the closer to a square.
- Prime factors
- 3² × 19
- Divisors
- 1, 3, 9, 19, 57, 171
- Sum of divisors
- 260
- Sum without itself
- 89
- Coprime below it
- 108
- Digit sum
- 9
- Digital root
- 9
- Roman numeral
- CLXXI
- Binary
- 10101011
- Octal
- 253
- Hexadecimal
- AB
- Base 36
- 4R
- Bits
- 8 bits
- Collatz steps
- 124 steps · peaks at 9,232
- Prime before
- 167
- Prime after
- 173
The grid
Ten per row, twenty rows. The filled cells are primes — you can see the multiples of 2 and 5 drop out in columns.
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Numbers either side
How to read this
- The prime factors are what the number is made of. The count and sum of divisors both follow from them.
- Add the divisors, take the number away, and you get perfect, abundant or deficient.
- The length of the binary form is the bit count. 255 taking eight digits is what a byte is.
- Collatz: halve it if even, triple it and add one if odd. The count is how many moves reach 1.
Frequently asked questions
Q. Is 171 a prime number?
No. It breaks down into 3² × 19.
Q. What are the divisors of 171?
1, 3, 9, 19, 57, 171 — 6 divisors in all, adding up to 260.
Q. How is 171 written in binary?
10101011, which is 8 bits. In hexadecimal it is AB.
Q. How many Collatz steps does 171 take?
It reaches 1 in 124, peaking at 9,232 on the way.