688
+688 is the international calling code for Tuvalu.
- Even
- Composite
Where 688 fits
Why 688 is special
Tuvalu is among the smallest and lowest-lying countries, and earns a substantial share of national revenue from licensing its .tv internet domain.
Factors & digit properties
- Divisors (10)
- 1, 2, 4, 8, 16, 43, 86, 172, 344, 688
- Prime factorisation
- 2^4 × 43
- Digit sum
- 22
- Digital root
- 4
Representations
- Decimal
- 688
- Scientific notation
- 6.880 × 10^2
Roman numerals
D C L X X X V I I I
Binary
1 0 1 0 1 1 0 0 0 0
1 × 512 + 0 × 256 + 1 × 128 + 0 × 64 + 1 × 32 + 1 × 16 + 0 × 8 + 0 × 4 + 0 × 2 + 0 × 1 = 688
Octal
1 2 6 0
1 × 512 + 2 × 64 + 6 × 8 + 0 × 1 = 688
Hexadecimal
2 b 0
2 × 256 + b × 16 + 0 × 1 = 688
Read as powers of two: 512 + 128 + 32 + 16 = 688.
In historical numeral systems
Egyptian
6 coils of rope, 8 hobbles, 8 strokes
6 × 100 + 8 × 10 + 8 × 1 = 688. 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), 2 corner wedges + 8 vertical wedges (units place)
11 × 60 + 28 = 688. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
chi, then pi, then eta, marked as a numeral
chi-pi-eta + keraia
chi + pi + eta 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 pe, then het
tav-resh-pe-het
tav (400) + resh (200) + pe (80) + het (8) = 688, 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
- Deficient 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 690 →Other connections
- is associated with690
why?
Strength 0.50, confidence "high".
Geography
+688 reaches Tuvalu, which derives a meaningful part of government revenue from leasing the .tv domain — an accident of the ISO country code becoming commercially valuable.
DocumentedGeographyGeography: Tuvalu
Common questions
Is 688 a prime number?
No, 688 is not prime.
What are the factors of 688?
The factors of 688 are 1, 2, 4, 8, 16, 43, 86, 172, 344, 688.
What is 688 in Roman numerals?
688 in Roman numerals is DCLXXXVIII.
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