635
The Ediacaran period began about 635 million years ago.
- Odd
- Composite
Where 635 fits
Why 635 is special
It is the only period of the Precambrian defined by a physical marker in a rock section rather than by a chosen date, which makes it unusual in the geological timescale.
635 is part of
Factors & digit properties
- Divisors (4)
- 1, 5, 127, 635
- Prime factorisation
- 5 × 127
- Digit sum
- 14
- Digital root
- 5
Representations
- Decimal
- 635
- Scientific notation
- 6.350 × 10^2
Roman numerals
D C X X X V
Binary
1 0 0 1 1 1 1 0 1 1
1 × 512 + 0 × 256 + 0 × 128 + 1 × 64 + 1 × 32 + 1 × 16 + 1 × 8 + 0 × 4 + 1 × 2 + 1 × 1 = 635
Octal
1 1 7 3
1 × 512 + 1 × 64 + 7 × 8 + 3 × 1 = 635
Hexadecimal
2 7 b
2 × 256 + 7 × 16 + b × 1 = 635
Read as powers of two: 512 + 64 + 32 + 16 + 8 + 2 + 1 = 635.
In historical numeral systems
Egyptian
6 coils of rope, 3 hobbles, 5 strokes
6 × 100 + 3 × 10 + 5 × 1 = 635. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
1 corner wedge (sixties place), 3 corner wedges + 5 vertical wedges (units place)
10 × 60 + 35 = 635. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
chi, then lambda, then epsilon, marked as a numeral
chi-lambda-epsilon + keraia
chi + lambda + epsilon 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 resh, then lamed, then he
tav-resh-lamed-he
tav (400) + resh (200) + lamed (30) + he (5) = 635, 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
- Happy number
- Semiprime
Related numbers & connections
One marks where the rock record begins and the other the only Precambrian period with a physical boundary marker.
View 3800 →Science
The Ediacaran, ratified in 2004, begins at the base of a cap carbonate following Marinoan glaciation and is defined by a Global Boundary Stratotype Section and Point in South Australia.
DocumentedScienceGeography: Global; type section in South AustraliaPeriod: ratified 2004
Common questions
Is 635 a prime number?
No, 635 is not prime.
What are the factors of 635?
The factors of 635 are 1, 5, 127, 635.
What is 635 in Roman numerals?
635 in Roman numerals is DCXXXV.
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