189
CLXXXIX
10111101
The number 189 — factors and divisors
Deficient
189 = 3³ × 7. It has 8 divisors, adding up to 320.
Its divisors, itself excluded, add up to less than the number.
Laid out as dots
It fits as 9 × 21. The more divisors, the closer to a square.
- Prime factors
- 3³ × 7
- Divisors
- 1, 3, 7, 9, 21, 27, 63, 189
- Sum of divisors
- 320
- Sum without itself
- 131
- Coprime below it
- 108
- Digit sum
- 18
- Digital root
- 9
- Roman numeral
- CLXXXIX
- Binary
- 10111101
- Octal
- 275
- Hexadecimal
- BD
- Base 36
- 59
- Bits
- 8 bits
- Collatz steps
- 106 steps · peaks at 9,232
- Prime before
- 181
- Prime after
- 191
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 189 a prime number?
No. It breaks down into 3³ × 7.
Q. What are the divisors of 189?
1, 3, 7, 9, 21, 27, 63, 189 — 8 divisors in all, adding up to 320.
Q. How is 189 written in binary?
10111101, which is 8 bits. In hexadecimal it is BD.
Q. How many Collatz steps does 189 take?
It reaches 1 in 106, peaking at 9,232 on the way.