381
+381 is the international calling code for Serbia.
- Odd
- Composite
Where 381 fits
Why 381 is special
Serbia inherited the +381 code that had covered all of Yugoslavia, while the successor states took new ones from the same 38x block.
Factors & digit properties
- Divisors (4)
- 1, 3, 127, 381
- Prime factorisation
- 3 × 127
- Digit sum
- 12
- Digital root
- 3
Representations
- Decimal
- 381
- Scientific notation
- 3.810 × 10^2
Roman numerals
C C C L X X X I
Binary
1 0 1 1 1 1 1 0 1
1 × 256 + 0 × 128 + 1 × 64 + 1 × 32 + 1 × 16 + 1 × 8 + 1 × 4 + 0 × 2 + 1 × 1 = 381
Octal
5 7 5
5 × 64 + 7 × 8 + 5 × 1 = 381
Hexadecimal
1 7 d
1 × 256 + 7 × 16 + d × 1 = 381
Read as powers of two: 256 + 64 + 32 + 16 + 8 + 4 + 1 = 381.
In historical numeral systems
Egyptian
3 coils of rope, 8 hobbles, 1 stroke
3 × 100 + 8 × 10 + 1 × 1 = 381. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
6 vertical wedges (sixties place), 2 corner wedges + 1 vertical wedge (units place)
6 × 60 + 21 = 381. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
tau, then pi, then alpha, marked as a numeral
tau-pi-alpha + keraia
tau + pi + alpha written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
shin, then pe, then alef
shin-pe-alef
shin (300) + pe (80) + alef (1) = 381, written in descending order.
Maya
3 bars + 4 dots (upper, twenties place) over 1 dot (lower, units place)
19 × 20 + 1 = 381. Places stack vertically with the smallest at the bottom, so the upper group is worth twenty times the lower.
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
- Semiprime
Related numbers & connections
Albania and Serbia are neighbours whose relationship is dominated by the disputed status of Kosovo, which was assigned +383 only in 2016.
View 355 →Nearby in a sequence
- is adjacent to355
why?
Strength 0.50, confidence "high".
Geography
+381 reaches Serbia, which retained Yugoslavia's original code while Croatia, Slovenia, Bosnia, North Macedonia and Montenegro were each assigned new numbers in the same range.
DocumentedGeographyGeography: Serbia
Mathematics
The Rubik's Cube can always be solved in at most 20 moves counting a half-turn as one move, or 26 counting only quarter-turns. Quoting one figure without the metric is the usual error.
DocumentedMathematics
Common questions
Is 381 a prime number?
No, 381 is not prime.
What are the factors of 381?
The factors of 381 are 1, 3, 127, 381.
What is 381 in Roman numerals?
381 in Roman numerals is CCCLXXXI.
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