84
84 is the atomic number of polonium, discovered in 1898 by Marie and Pierre Curie and named after Marie Curie's native Poland.
- Even
- Composite
Where 84 fits
Why 84 is special
84's element carries real history: polonium was the first chemical element ever named to highlight a political cause.
Same number, different meanings
How 84 is understood across different contexts — never implying one meaning because of another.
- Mathematics
84's element carries real history: polonium was the first chemical element ever named to highlight a political cause.
- History
Polonium was discovered in 1898 by Marie and Pierre Curie, who named it after Marie Curie's native Poland — the first element named to highlight a political cause.
- Science
84 is the atomic number of polonium, an intensely radioactive element so rare in nature that isolating it required processing tonnes of uranium ore.
Factors & digit properties
- Divisors (12)
- 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84
- Prime factorisation
- 2^2 × 3 × 7
- Digit sum
- 12
- Digital root
- 3
Representations
- Decimal
- 84
- Scientific notation
- 8.400 × 10^1
Roman numerals
L X X X I V
LXXXIV uses the subtractive pair IV: one before five — five minus one.
Binary
1 0 1 0 1 0 0
1 × 64 + 0 × 32 + 1 × 16 + 0 × 8 + 1 × 4 + 0 × 2 + 0 × 1 = 84
Octal
1 2 4
1 × 64 + 2 × 8 + 4 × 1 = 84
Hexadecimal
5 4
5 × 16 + 4 × 1 = 84
Read as powers of two: 64 + 16 + 4 = 84.
In historical numeral systems
Egyptian
8 hobbles, 4 strokes
8 × 10 + 4 × 1 = 84. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
1 vertical wedge (sixties place), 2 corner wedges + 4 vertical wedges (units place)
1 × 60 + 24 = 84. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
pi, then delta, marked as a numeral
pi-delta + keraia
pi + delta written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
pe, then dalet
pe-dalet
pe (80) + dalet (4) = 84, written in descending order.
Chinese numerals
bā shí sì
bā shí sì
八 before 十 multiplies it: 8 tens. 四 after it adds 4. The written form mirrors the arithmetic — "bā shí sì". The financial (anti-fraud) form is 捌拾肆.
Maya
4 dots (upper, twenties place) over 4 dots (lower, units place)
4 × 20 + 4 = 84. 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
- Abundant number
- Harshad (Niven) number
Related numbers & connections
42 is a factor of 84 (42 × 2 = 84).
View 42 →Mathematically related
- has factor42
why?
Strength 0.50, confidence "high".
History
Polonium was discovered in 1898 by Marie and Pierre Curie, who named it after Marie Curie's native Poland — the first element named to highlight a political cause.
DocumentedHistoryPeriod: 1898
Science
84 is the atomic number of polonium, an intensely radioactive element so rare in nature that isolating it required processing tonnes of uranium ore.
DocumentedScience
Common questions
Is 84 a prime number?
No, 84 is not prime.
What are the factors of 84?
The factors of 84 are 1, 2, 3, 4, 6, 7, 12, 14, 21, 28, 42, 84.
What is 84 in Roman numerals?
84 in Roman numerals is LXXXIV. IV is subtractive: one before five — five minus one. Written additively it would be LXXXIIII, which Roman inscriptions used freely — the strict subtractive form is a later convention.
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