Overview
500 is the integer following 499 and preceding 501. In common usage it is spoken as "five hundred" and written in Roman numerals as D. As a round three-digit number it is frequently used as a milestone (half a millennium) and in everyday counting, recordkeeping and labeling.
Mathematical characteristics
Five hundred is an even, composite number. Its prime factorization is 2^2 × 5^3, and its positive divisors are 1, 2, 4, 5, 10, 20, 25, 50, 100, 125, 250 and 500. The sum of its proper divisors exceeds the number itself, so 500 is classified as an abundant number. In binary it is 111110100 and in hexadecimal it is 1F4.
Representations and terms
The Latin term for 500 is quingenti, and the English anniversary term is quincentenary or quincentennial for a 500th anniversary. In notation and computing contexts 500 commonly appears in error codes (for example the HTTP "500 Internal Server Error") and as a simple round base for estimates or limits.
Uses, examples and cultural notes
Beyond arithmetic, 500 is used as a label for sporting events (for example the Indianapolis 500 and the Daytona 500), as a benchmark number in lists or rankings, and as a milestone in publishing or commemorations. Its size also makes 500! (factorial) astronomically large, so the number frequently serves in combinatorial examples to illustrate growth of permutations and combinations.
Notable facts and distinctions
As a half-millennium, 500 years marks significant historical anniversaries. Mathematically it is not a perfect square or triangular number. Its Roman numeral form, D, derives from the system used by ancient Rome and remains the concise classical notation for this value. For further numerical context and references, see related resources linked from this article.