77
LXXVII
1001101
The number 77 — factors and divisors
Deficient
77 = 7 × 11. It has 4 divisors, adding up to 96.
Its divisors, itself excluded, add up to less than the number.
Laid out as dots
It fits as 7 × 11. The more divisors, the closer to a square.
- Prime factors
- 7 × 11
- Divisors
- 1, 7, 11, 77
- Sum of divisors
- 96
- Sum without itself
- 19
- Coprime below it
- 60
- Digit sum
- 14
- Digital root
- 5
- Roman numeral
- LXXVII
- Binary
- 1001101
- Octal
- 115
- Hexadecimal
- 4D
- Base 36
- 25
- Bits
- 7 bits
- Collatz steps
- 22 steps · peaks at 232
- 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 77 a prime number?
No. It breaks down into 7 × 11.
Q. What are the divisors of 77?
1, 7, 11, 77 — 4 divisors in all, adding up to 96.
Q. How is 77 written in binary?
1001101, which is 7 bits. In hexadecimal it is 4D.
Q. How many Collatz steps does 77 take?
It reaches 1 in 22, peaking at 232 on the way.