75
LXXV
1001011
The number 75 — factors and divisors
Deficient
75 = 3 × 5². It has 6 divisors, adding up to 124.
Its divisors, itself excluded, add up to less than the number.
Laid out as dots
It fits as 5 × 15. The more divisors, the closer to a square.
- Prime factors
- 3 × 5²
- Divisors
- 1, 3, 5, 15, 25, 75
- Sum of divisors
- 124
- Sum without itself
- 49
- Coprime below it
- 40
- Digit sum
- 12
- Digital root
- 3
- Roman numeral
- LXXV
- Binary
- 1001011
- Octal
- 113
- Hexadecimal
- 4B
- Base 36
- 23
- Bits
- 7 bits
- Collatz steps
- 14 steps · peaks at 340
- Prime before
- 73
- Prime after
- 79
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 75 a prime number?
No. It breaks down into 3 × 5².
Q. What are the divisors of 75?
1, 3, 5, 15, 25, 75 — 6 divisors in all, adding up to 124.
Q. How is 75 written in binary?
1001011, which is 7 bits. In hexadecimal it is 4B.
Q. How many Collatz steps does 75 take?
It reaches 1 in 14, peaking at 340 on the way.