Numberwise

6,371

6371 kilometres is the mean radius of the Earth, the figure most calculations use.

2 confirmed records · 2 sourcesChecked and sourcedChecked, general knowledgeHow we qualify claimsReport a correction

Where 6,371 fits

Where 6,371 fits: Mathematics, ScienceMathematics: Semiprime. Science: Space and astronomy.MathematicsSemiprimeScienceSpace and astronomy6,371
6,371 connects to 2 worlds: mathematics, science.

Why 6,371 is special

6371 km is a single number standing in for a shape that is not a sphere. The Earth bulges at the equator: the equatorial radius is about 6,378 km and the polar radius about 6,357 km, a difference of roughly 21 km. The mean value of 6,371 km is what navigation, mapping and great-circle distance formulas use when treating the planet as round is close enough.

6,371 is part of

Numbers around us

Factors & digit properties

Divisors (4)
1, 23, 277, 6371
Prime factorisation
23 × 277
Digit sum
17
Digital root
8

Representations

Decimal
6371
Scientific notation
6.371 × 10^3

Roman numerals

Roman numerals as modelled here goes up to 3,999.

Binary

1 1 0 0 0 1 1 1 0 0 0 1 1

1 × 4,096 + 1 × 2,048 + 0 × 1,024 + 0 × 512 + 0 × 256 + 1 × 128 + 1 × 64 + 1 × 32 + 0 × 16 + 0 × 8 + 0 × 4 + 1 × 2 + 1 × 1 = 6,371

Octal

1 4 3 4 3

1 × 4,096 + 4 × 512 + 3 × 64 + 4 × 8 + 3 × 1 = 6,371

Hexadecimal

1 8 e 3

1 × 4,096 + 8 × 256 + e × 16 + 3 × 1 = 6,371

Read as powers of two: 4,096 + 2,048 + 128 + 64 + 32 + 2 + 1 = 6,371.

In historical numeral systems

Egyptian

6 lotuses, 3 coils of rope, 7 hobbles, 1 stroke

6 × 1,000 + 3 × 100 + 7 × 10 + 1 × 1 = 6,371. 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

Related numbers & connections

Documented appearance
6371 appears in Numbers in space, the topic covering numbers that carry a documented astronomy fact.

6371 appears in Numbers in space, the topic covering numbers that carry a documented astronomy fact.

Numbers Around Us

  • appears inSpace and astronomy
    why?

    Strength 0.50, confidence "high".

How is 6,371 connected to another number? →

Science

  • The mean radius of the Earth is about 6371 kilometres (worldwide, IUGG reference figure). A mean, because the Earth is not a sphere: the equatorial radius is about 21 kilometres greater than the polar one, which is the same flattening that makes the equatorial circumference the longer of the two.

    DocumentedScienceGeography: worldwide, IUGG reference figure

  • Earth is an oblate spheroid: about 6,378 km at the equator and 6,357 km pole to pole, a difference of roughly 21 kilometres caused by rotation. 6,371 km is the mean value used when a spherical approximation is good enough — great-circle distances, satellite orbit rules of thumb — while surveying and GPS use the full WGS 84 ellipsoid instead.

    DocumentedScience

Common questions

Is 6,371 a prime number?

No, 6,371 is not prime.

What are the factors of 6,371?

The factors of 6,371 are 1, 23, 277, 6371.

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