83
83 is a prime number and the atomic number of bismuth — long assumed stable until 2003 measurements found it extremely weakly radioactive.
- Odd
- Prime
Where 83 fits
Why 83 is special
83's element, bismuth, is a genuine case of scientific correction: its 'stable' status held for over a century before precise measurement overturned it, though its half-life still vastly exceeds the age of the universe.
83 connects to:
- 82 — is adjacent to
Same number, different meanings
How 83 is understood across different contexts — never implying one meaning because of another.
- Mathematics
83's element, bismuth, is a genuine case of scientific correction: its 'stable' status held for over a century before precise measurement overturned it, though its half-life still vastly exceeds the age of the universe.
- Everyday life
Element 83 is the heaviest element that is, for practical purposes, non-toxic — which is unusual for a heavy metal and is why bismuth subsalicylate is sold over the counter for indigestion, and why the medicine turns the tongue black (a harmless sulfide, not a warning sign). The same low toxicity has made bismuth the standard substitute for lead in plumbing solder, shot and fishing weights as lead has been restricted.
- Technology & computing
Bismuth is one of the very few substances that expands as it solidifies, and alloyed with lead, tin and cadmium it produces metals that melt below the boiling point of water. Those alloys are what makes a fire sprinkler work: a small plug melts at a set temperature and releases the water. The same low melting point is used in safety fuses and in castings that need to be melted out afterwards.
- Science
83 is the atomic number of bismuth, long assumed completely stable until 2003 measurements found it to be extremely weakly radioactive, with a half-life far longer than the age of the universe.
83 is part of
Factors & digit properties
- Divisors (2)
- 1, 83
- Prime factorisation
- 83
- Digit sum
- 11
- Digital root
- 2
Representations
- Decimal
- 83
- Scientific notation
- 8.300 × 10^1
Roman numerals
L X X X I I I
Binary
1 0 1 0 0 1 1
1 × 64 + 0 × 32 + 1 × 16 + 0 × 8 + 0 × 4 + 1 × 2 + 1 × 1 = 83
Octal
1 2 3
1 × 64 + 2 × 8 + 3 × 1 = 83
Hexadecimal
5 3
5 × 16 + 3 × 1 = 83
Read as powers of two: 64 + 16 + 2 + 1 = 83.
In historical numeral systems
Egyptian
8 hobbles, 3 strokes
8 × 10 + 3 × 1 = 83. 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 + 3 vertical wedges (units place)
1 × 60 + 23 = 83. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
pi, then gamma, marked as a numeral
pi-gamma + keraia
pi + gamma 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 gimel
pe-gimel
pe (80) + gimel (3) = 83, written in descending order.
Chinese numerals
bā shí sān
bā shí sān
八 before 十 multiplies it: 8 tens. 三 after it adds 3. The written form mirrors the arithmetic — "bā shí sān". The financial (anti-fraud) form is 捌拾參.
Maya
4 dots (upper, twenties place) over 3 dots (lower, units place)
4 × 20 + 3 = 83. 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
- Sophie Germain prime
- Safe prime
Related numbers & connections
83 and 82 are consecutive integers.
View 82 →Nearby in a sequence
- is adjacent to82
why?
Strength 0.50, confidence "high".
Everyday life
Element 83 is the heaviest element that is, for practical purposes, non-toxic — which is unusual for a heavy metal and is why bismuth subsalicylate is sold over the counter for indigestion, and why the medicine turns the tongue black (a harmless sulfide, not a warning sign). The same low toxicity has made bismuth the standard substitute for lead in plumbing solder, shot and fishing weights as lead has been restricted.
DocumentedEveryday life
Technology & computing
Bismuth is one of the very few substances that expands as it solidifies, and alloyed with lead, tin and cadmium it produces metals that melt below the boiling point of water. Those alloys are what makes a fire sprinkler work: a small plug melts at a set temperature and releases the water. The same low melting point is used in safety fuses and in castings that need to be melted out afterwards.
DocumentedTechnology & computing
Science
83 is the atomic number of bismuth, long assumed completely stable until 2003 measurements found it to be extremely weakly radioactive, with a half-life far longer than the age of the universe.
DocumentedScience
Mathematics
83 is prime — the 23rd prime number.
DocumentedMathematics
Common questions
Why does bismuth medicine turn your tongue black?
Bismuth reacts with trace sulfur in saliva to form bismuth sulfide, which is black. It is harmless and washes off, and it affects the stool the same way. Bismuth is the heaviest element that is effectively non-toxic, which is unusual for a heavy metal and is why it can be sold over the counter at all.
How does a fire sprinkler know when to go off?
A small plug of low-melting-point alloy holds it shut, and heat melts it. Those alloys are mostly bismuth — element 83 — which with lead, tin and cadmium produces metals that melt below the boiling point of water. Each sprinkler head operates on its own, which is why a real fire sets off the heads above it rather than the whole building's.
Is 83 a prime number?
Yes, 83 is prime — it has exactly two positive divisors: 1 and itself.
What are the factors of 83?
The factors of 83 are 1, 83.
What is 83 in Roman numerals?
83 in Roman numerals is LXXXIII.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 4 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 15 July 2026