2818
RFC 2818 defines HTTP over TLS.
- Even
- Composite
Where 2818 fits
Why 2818 is special
It specifies how a certificate is checked against the hostname requested, which is the step that makes the padlock mean anything. Skipping it is how man-in-the-middle attacks succeed against otherwise encrypted connections.
Same number, different meanings
How 2818 is understood across different contexts — never implying one meaning because of another.
- Mathematics
It specifies how a certificate is checked against the hostname requested, which is the step that makes the padlock mean anything. Skipping it is how man-in-the-middle attacks succeed against otherwise encrypted connections.
- Technology & computing
RFC 2818 defines verifying that the certificate presented actually belongs to the site requested. Encryption without that check protects the channel to an attacker just as well as to the intended server.
- Science
NGC 2818 is a planetary nebula projected against an open cluster. Whether it is physically a member has been disputed, since a cluster old enough to produce it should have dispersed.
2818 is part of
Factors & digit properties
- Divisors (4)
- 1, 2, 1409, 2818
- Prime factorisation
- 2 × 1409
- Digit sum
- 19
- Digital root
- 1
Representations
- Decimal
- 2818
- Scientific notation
- 2.818 × 10^3
Roman numerals
M M D C C C X V I I I
Binary
1 0 1 1 0 0 0 0 0 0 1 0
1 × 2,048 + 0 × 1,024 + 1 × 512 + 1 × 256 + 0 × 128 + 0 × 64 + 0 × 32 + 0 × 16 + 0 × 8 + 0 × 4 + 1 × 2 + 0 × 1 = 2,818
Octal
5 4 0 2
5 × 512 + 4 × 64 + 0 × 8 + 2 × 1 = 2,818
Hexadecimal
b 0 2
b × 256 + 0 × 16 + 2 × 1 = 2,818
Read as powers of two: 2,048 + 512 + 256 + 2 = 2,818.
In historical numeral systems
Egyptian
2 lotuses, 8 coils of rope, 1 hobble, 8 strokes
2 × 1,000 + 8 × 100 + 1 × 10 + 8 × 1 = 2,818. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
4 corner wedges + 6 vertical wedges (sixties place), 5 corner wedges + 8 vertical wedges (units place)
46 × 60 + 58 = 2818. Places are separated by a space on the tablet, with the higher place written first.
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
HTTP over TLS is what the padlock refers to, and the certificate check is what makes it mean anything.
HSTS closes the plaintext window that HTTP over TLS otherwise leaves open on a first visit.
View 6797 →Technology & computing
RFC 2818 defines verifying that the certificate presented actually belongs to the site requested. Encryption without that check protects the channel to an attacker just as well as to the intended server.
DocumentedTechnology & computingPeriod: 2000
Science
NGC 2818 is a planetary nebula projected against an open cluster. Whether it is physically a member has been disputed, since a cluster old enough to produce it should have dispersed.
DocumentedSciencePeriod: 1826–
Common questions
Is 2818 a prime number?
No, 2818 is not prime.
What are the factors of 2818?
The factors of 2818 are 1, 2, 1409, 2818.
What is 2818 in Roman numerals?
2818 in Roman numerals is MMDCCCXVIII.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 2 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026