5545
RFC 5545 defines the iCalendar data format.
- Odd
- Composite
Where 5545 fits
Why 5545 is special
Every meeting invitation that arrives as an .ics attachment is this format, including its notoriously awkward rules for repeating events.
5545 is part of
Factors & digit properties
- Divisors (4)
- 1, 5, 1109, 5545
- Prime factorisation
- 5 × 1109
- Digit sum
- 19
- Digital root
- 1
Representations
- Decimal
- 5545
- Scientific notation
- 5.545 × 10^3
Roman numerals
Roman numerals as modelled here goes up to 3,999.
Binary
1 0 1 0 1 1 0 1 0 1 0 0 1
1 × 4,096 + 0 × 2,048 + 1 × 1,024 + 0 × 512 + 1 × 256 + 1 × 128 + 0 × 64 + 1 × 32 + 0 × 16 + 1 × 8 + 0 × 4 + 0 × 2 + 1 × 1 = 5,545
Octal
1 2 6 5 1
1 × 4,096 + 2 × 512 + 6 × 64 + 5 × 8 + 1 × 1 = 5,545
Hexadecimal
1 5 a 9
1 × 4,096 + 5 × 256 + a × 16 + 9 × 1 = 5,545
Read as powers of two: 4,096 + 1,024 + 256 + 128 + 32 + 8 + 1 = 5,545.
In historical numeral systems
Egyptian
5 lotuses, 5 coils of rope, 4 hobbles, 5 strokes
5 × 1,000 + 5 × 100 + 4 × 10 + 5 × 1 = 5,545. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Systems that simply cannot reach this value are left out. Where a script needs a font most readers do not have, the reading is given instead of the glyphs — see number systems for each system in full.
Other mathematical patterns
- Deficient number
- Happy number
- Semiprime
Related numbers & connections
Both document interchange formats that were in wide use before anyone specified them, and both are weaker for it.
View 4180 →Technology & computing
RFC 5545 specifies iCalendar, including the RRULE property that expresses repeating events. Recurrence combined with time zones and daylight saving is the format's most common source of interoperability failure.
DocumentedTechnology & computingGeography: International — IETFPeriod: 2009
Common questions
Is 5545 a prime number?
No, 5545 is not prime.
What are the factors of 5545?
The factors of 5545 are 1, 5, 1109, 5545.
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: 15 July 2026