7805
The 7805 is a fixed five-volt linear voltage regulator.
- Odd
- Composite
Where 7805 fits
Why 7805 is special
It wastes the difference between input and output as heat, which is both its great simplicity and the reason switching regulators replaced it in battery equipment.
Factors & digit properties
- Divisors (8)
- 1, 5, 7, 35, 223, 1115, 1561, 7805
- Prime factorisation
- 5 × 7 × 223
- Digit sum
- 20
- Digital root
- 2
Representations
- Decimal
- 7805
- Binary
- 1111001111101
- Octal
- 17175
- Hexadecimal
- 1e7d
- Scientific notation
- 7.805 × 10^3
Other mathematical patterns
- Deficient number
Related numbers & connections
The last two digits of a 78xx part are its output voltage, so the family is read directly from the number.
View 7812 →The 723 gave access to its internal reference and error amplifier, which the fixed three-terminal regulators that followed hid away.
View 723 →Technology & computing
The 7805 is part of the 78xx family of three-terminal positive regulators. It dissipates the excess input voltage as heat, so efficiency falls as the input-output difference grows.
DocumentedTechnology & computingPeriod: 1970s–
Common questions
Is 7805 a prime number?
No, 7805 is not prime.
What are the factors of 7805?
The factors of 7805 are 1, 5, 7, 35, 223, 1115, 1561, 7805.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 3 August 2026