6,371
6371 kilometres is the mean radius of the Earth, the figure most calculations use.
- Odd
- Composite
Where 6,371 fits
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.
Factors & digit properties
- Divisors (4)
- 1, 23, 277, 6371
- Prime factorisation
- 23 × 277
- Digit sum
- 17
- Digital root
- 8
Representations
- Decimal
- 6371
- Binary
- 1100011100011
- Octal
- 14343
- Hexadecimal
- 18e3
- Scientific notation
- 6.371 × 10^3
Other mathematical patterns
- Deficient number
- Semiprime
Science
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: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 3 August 2026