51
LI
110011
The number 51 — factors and divisors
Deficient
51 = 3 × 17. It has 4 divisors, adding up to 72.
Its divisors, itself excluded, add up to less than the number.
Laid out as dots
It fits as 3 × 17. The more divisors, the closer to a square.
- Prime factors
- 3 × 17
- Divisors
- 1, 3, 17, 51
- Sum of divisors
- 72
- Sum without itself
- 21
- Coprime below it
- 32
- Digit sum
- 6
- Digital root
- 6
- Roman numeral
- LI
- Binary
- 110011
- Octal
- 63
- Hexadecimal
- 33
- Base 36
- 1F
- Bits
- 6 bits
- Collatz steps
- 24 steps · peaks at 232
- Prime before
- 47
- Prime after
- 53
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 51 a prime number?
No. It breaks down into 3 × 17.
Q. What are the divisors of 51?
1, 3, 17, 51 — 4 divisors in all, adding up to 72.
Q. How is 51 written in binary?
110011, which is 6 bits. In hexadecimal it is 33.
Q. How many Collatz steps does 51 take?
It reaches 1 in 24, peaking at 232 on the way.