643
643 is the ISO 3166-1 numeric country code for Russia.
- Odd
- Prime
Where 643 fits
Why 643 is special
Russia inherited the Soviet Union's seat in most international systems but not its country code — the USSR's code was retired and Russia assigned a new one.
643 is part of
Factors & digit properties
- Divisors (2)
- 1, 643
- Prime factorisation
- 643
- Digit sum
- 13
- Digital root
- 4
Representations
- Decimal
- 643
- Binary
- 1010000011
- Octal
- 1203
- Hexadecimal
- 283
- Roman numeral
- DCXLIII
- Scientific notation
- 6.430 × 10^2
Other mathematical patterns
- Deficient number
- Lucky number (mathematical sieve)
- Twin prime
Related numbers & connections
Russia's ISO numeric code and calling code. Russia kept the Soviet calling code +7 and was assigned a new ISO code, so the two systems took opposite decisions about succession.
View 7 →Other connections
- is associated with7
why?
Strength 0.50, confidence "high".
Geography
643 is Russia's ISO numeric code. The Soviet code was retired rather than transferred, which is a small technical statement about succession that took diplomats considerably longer to settle.
DocumentedGeographyGeography: Russia
Common questions
Is 643 a prime number?
Yes, 643 is prime — it has exactly two positive divisors: 1 and itself.
What are the factors of 643?
The factors of 643 are 1, 643.
What is 643 in Roman numerals?
643 in Roman numerals is DCXLIII.
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