6400
The Amazon is about 6,400 km long and carries more water than the next several rivers combined.
Where 6400 fits
Why 6400 is special
Its discharge is around a fifth of all river water reaching the oceans. On volume there is no argument about its rank; only the length is contested.
6400 is part of
Factors & digit properties
- Divisors (27)
- 1, 2, 4, 5, 8, 10, 16, 20, 25, 32, 40, 50, 64, 80, 100, 128, 160, 200, 256, 320, 400, 640, 800, 1280, 1600, 3200, 6400
- Prime factorisation
- 2^8 × 5^2
- Digit sum
- 10
- Digital root
- 1
Representations
- Decimal
- 6400
- Scientific notation
- 6.400 × 10^3
Roman numerals
Roman numerals as modelled here goes up to 3,999.
Binary
1 1 0 0 1 0 0 0 0 0 0 0 0
1 × 4,096 + 1 × 2,048 + 0 × 1,024 + 0 × 512 + 1 × 256 + 0 × 128 + 0 × 64 + 0 × 32 + 0 × 16 + 0 × 8 + 0 × 4 + 0 × 2 + 0 × 1 = 6,400
Octal
1 4 4 0 0
1 × 4,096 + 4 × 512 + 4 × 64 + 0 × 8 + 0 × 1 = 6,400
Hexadecimal
1 9 0 0
1 × 4,096 + 9 × 256 + 0 × 16 + 0 × 1 = 6,400
Read as powers of two: 4,096 + 2,048 + 256 = 6,400.
In historical numeral systems
Egyptian
6 lotuses, 4 coils of rope
6 × 1,000 + 4 × 100 = 6,400. 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
- Abundant number
- Powerful number
- Harshad (Niven) number
Related numbers & connections
The Nile and the Amazon are the two claimants to longest river, and the dispute is definitional — where each begins and which tributary counts.
View 6650 →Geography
The Amazon discharges roughly a fifth of all freshwater entering the world's oceans, more than the next several rivers together. Its length is argued about and its volume is not.
DocumentedGeographyGeography: South America
Common questions
Is 6400 a prime number?
No, 6400 is not prime.
What are the factors of 6400?
The factors of 6400 are 1, 2, 4, 5, 8, 10, 16, 20, 25, 32, 40, 50, 64, 80, 100, 128, 160, 200, 256, 320, 400, 640, 800, 1280, 1600, 3200, 6400.
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