169
CLXIX
10101001
The number 169 — factors and divisors
Deficient
169 = 13². It has 3 divisors, adding up to 183.
Its divisors, itself excluded, add up to less than the number.
Families it belongs to
Square
A number times itself — the dots lay out as a square.
Laid out as dots
It fits as 13 × 13. The more divisors, the closer to a square.
- Prime factors
- 13²
- Divisors
- 1, 13, 169
- Sum of divisors
- 183
- Sum without itself
- 14
- Coprime below it
- 156
- Digit sum
- 16
- Digital root
- 7
- Roman numeral
- CLXIX
- Binary
- 10101001
- Octal
- 251
- Hexadecimal
- A9
- Base 36
- 4P
- Bits
- 8 bits
- Collatz steps
- 49 steps · peaks at 4,372
- 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 169 a prime number?
No. It breaks down into 13².
Q. What are the divisors of 169?
1, 13, 169 — 3 divisors in all, adding up to 183.
Q. How is 169 written in binary?
10101001, which is 8 bits. In hexadecimal it is A9.
Q. How many Collatz steps does 169 take?
It reaches 1 in 49, peaking at 4,372 on the way.