541
541 is the year the Plague of Justinian began.
- Odd
- Prime
Where 541 fits
Why 541 is special
It is the first recorded pandemic of bubonic plague, and DNA from burials has confirmed the same bacterium as the Black Death. Estimates of mortality vary enormously and recent scholarship argues the traditional figures are far too high.
541 is part of
Factors & digit properties
- Divisors (2)
- 1, 541
- Prime factorisation
- 541
- Digit sum
- 10
- Digital root
- 1
Representations
- Decimal
- 541
- Scientific notation
- 5.410 × 10^2
Roman numerals
D X L I
DXLI uses the subtractive pair XL: ten before fifty — fifty minus ten.
Binary
1 0 0 0 0 1 1 1 0 1
1 × 512 + 0 × 256 + 0 × 128 + 0 × 64 + 0 × 32 + 1 × 16 + 1 × 8 + 1 × 4 + 0 × 2 + 1 × 1 = 541
Octal
1 0 3 5
1 × 512 + 0 × 64 + 3 × 8 + 5 × 1 = 541
Hexadecimal
2 1 d
2 × 256 + 1 × 16 + d × 1 = 541
Read as powers of two: 512 + 16 + 8 + 4 + 1 = 541.
In historical numeral systems
Egyptian
5 coils of rope, 4 hobbles, 1 stroke
5 × 100 + 4 × 10 + 1 × 1 = 541. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
9 vertical wedges (sixties place), 1 vertical wedge (units place)
9 × 60 + 1 = 541. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
phi, then mu, then alpha, marked as a numeral
phi-mu-alpha + keraia
phi + mu + alpha written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
tav, then qof, then mem, then alef
tav-qof-mem-alef
tav (400) + qof (100) + mem (40) + alef (1) = 541, written in descending order.
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
- Lucky number (mathematical sieve)
Related numbers & connections
The Antonine Plague from 165 and the Plague of Justinian from 541 are the two great pandemics of the classical Mediterranean. The pathogen of the first is still not identified; the second has been confirmed as Yersinia pestis from ancient DNA.
View 165 →History
Ancient DNA has confirmed that the plague beginning in 541 was Yersinia pestis, the same organism as the Black Death. How many it killed is now actively disputed, with recent work arguing the traditional catastrophic figures are unsupported.
DocumentedHistoryGeography: Byzantine Empire and MediterraneanPeriod: 541–549
Common questions
Is 541 a prime number?
Yes, 541 is prime — it has exactly two positive divisors: 1 and itself.
What are the factors of 541?
The factors of 541 are 1, 541.
What is 541 in Roman numerals?
541 in Roman numerals is DXLI. XL is subtractive: ten before fifty — fifty minus ten. Written additively it would be DXXXXI, 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: 1 reviewer-confirmed record, sourced and reviewed before publication.
Last reviewed: 15 July 2026