8721
8721 is the n-ary summation sign.
- Odd
- Composite
Where 8721 fits
Why 8721 is special
It is a distinct character from the Greek capital sigma, and using the letter instead is a common typesetting error that breaks mathematical search and screen readers.
Factors & digit properties
- Divisors (16)
- 1, 3, 9, 17, 19, 27, 51, 57, 153, 171, 323, 459, 513, 969, 2907, 8721
- Prime factorisation
- 3^3 × 17 × 19
- Digit sum
- 18
- Digital root
- 9
Representations
- Decimal
- 8721
- Binary
- 10001000010001
- Octal
- 21021
- Hexadecimal
- 2211
- Scientific notation
- 8.721 × 10^3
Other mathematical patterns
- Deficient number
Related numbers & connections
Summation and integration are the discrete and continuous forms of the same operation, and their symbols reflect it.
View 8747 →Both symbols were introduced by seventeenth-century mathematicians and encoded three centuries later.
View 8734 →Numbers Around Us
- appears alongside8747
why?
Strength 0.50, confidence "high".
Science
U+2211 N-ARY SUMMATION is the mathematical operator for summation, encoded separately from the Greek capital letter sigma despite near-identical appearance.
DocumentedScienceGeography: International — Unicode ConsortiumPeriod: 1991–
Common questions
Is 8721 a prime number?
No, 8721 is not prime.
What are the factors of 8721?
The factors of 8721 are 1, 3, 9, 17, 19, 27, 51, 57, 153, 171, 323, 459, 513, 969, 2907, 8721.
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: 3 August 2026