690
+690 is the international calling code for Tokelau.
- Even
- Composite
Where 690 fits
Why 690 is special
Tokelau ran the world's most-registered internet domain, .tk, by giving names away free, and became the first territory powered almost entirely by solar energy in 2012.
Same number, different meanings
How 690 is understood across different contexts — never implying one meaning because of another.
- Mathematics
Tokelau ran the world's most-registered internet domain, .tk, by giving names away free, and became the first territory powered almost entirely by solar energy in 2012.
- Culture
ISO 690 defines how to cite a source internationally. Academic disciplines overwhelmingly use their own house styles instead, which is why citation formatting remains a per-journal problem.
- Geography
+690 reaches Tokelau, whose free .tk domain registrations once made it nominally the largest country-code domain in the world, and which switched to near-total solar electricity in 2012.
Factors & digit properties
- Divisors (16)
- 1, 2, 3, 5, 6, 10, 15, 23, 30, 46, 69, 115, 138, 230, 345, 690
- Prime factorisation
- 2 × 3 × 5 × 23
- Digit sum
- 15
- Digital root
- 6
Representations
- Decimal
- 690
- Scientific notation
- 6.900 × 10^2
Roman numerals
D C X C
DCXC uses the subtractive pair XC: ten before a hundred — a hundred minus ten.
Binary
1 0 1 0 1 1 0 0 1 0
1 × 512 + 0 × 256 + 1 × 128 + 0 × 64 + 1 × 32 + 1 × 16 + 0 × 8 + 0 × 4 + 1 × 2 + 0 × 1 = 690
Octal
1 2 6 2
1 × 512 + 2 × 64 + 6 × 8 + 2 × 1 = 690
Hexadecimal
2 b 2
2 × 256 + b × 16 + 2 × 1 = 690
Read as powers of two: 512 + 128 + 32 + 16 + 2 = 690.
In historical numeral systems
Egyptian
6 coils of rope, 9 hobbles
6 × 100 + 9 × 10 = 690. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
1 corner wedge + 1 vertical wedge (sixties place), 3 corner wedges (units place)
11 × 60 + 30 = 690. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
chi, then koppa, marked as a numeral
chi-koppa + keraia
chi + koppa written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
tav, then resh, then tsadi
tav-resh-tsadi
tav (400) + resh (200) + tsadi (90) = 690, written in descending order.
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
- Abundant number
- Harshad (Niven) number
Related numbers & connections
Tuvalu and Tokelau both derive meaningful revenue from internet domains that happen to be commercially valuable — .tv and .tk — which is an accident of their ISO country codes.
View 688 →Other connections
- is associated with688
why?
Strength 0.50, confidence "high".
Culture
ISO 690 defines how to cite a source internationally. Academic disciplines overwhelmingly use their own house styles instead, which is why citation formatting remains a per-journal problem.
DocumentedCultureGeography: International — ISO member bodies
Geography
+690 reaches Tokelau, whose free .tk domain registrations once made it nominally the largest country-code domain in the world, and which switched to near-total solar electricity in 2012.
DocumentedGeographyGeography: Tokelau
Common questions
Is 690 a prime number?
No, 690 is not prime.
What are the factors of 690?
The factors of 690 are 1, 2, 3, 5, 6, 10, 15, 23, 30, 46, 69, 115, 138, 230, 345, 690.
What is 690 in Roman numerals?
690 in Roman numerals is DCXC. XC is subtractive: ten before a hundred — a hundred minus ten. Written additively it would be DCLXXXX, which Roman inscriptions used freely — the strict subtractive form is a later convention.
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