Number reference
404 explained.
404: four hundred four, composite; factors, prime factorization, roots, binary, hexadecimal, and digit properties.
Identity and representations
- Written form
- four hundred four
- Classification
- composite
- Factors
- 1, 2, 4, 101, 202, 404
- Prime factorization
- 2 × 2 × 101
- Square root
- 20.099751
- Cube root
- 7.392542
- Binary
- 110010100
- Octal
- 624
- Hexadecimal
- 194
- Roman numeral
- CDIV
- Digit sum
- 8
- Digital root
- 8
What makes 404 notable
- Factor structure. 404 breaks down into 2 distinct primes (2, 101) and has 6 divisors in total, so it can be split into equal whole-number groups 4 ways beyond 1 and itself.
404 in everyday use
Four hundred four is the most famous error code on the internet. HTTP 404 Not Found is what a web server returns when the address is valid but nothing lives there, and it has become an everyday idiom for anything missing. The number appears in Chinese internet slang as a byword for content that has been removed, and in some cities the 404 area code or bus route gets the joke attached to it. A persistent legend that it refers to room 404 at CERN has been denied by the people who were there.
The number is a palindrome and factors as 2² × 101, with six divisors: 1, 2, 4, 101, 202, and 404. It is a sum of two squares, 20² + 2² = 400 + 4, and since 101 is prime it is four times a prime. It is 110010100 in binary and 194 in hexadecimal, its digit sum is 8, and it lies between the primes 401 and 409, in the stretch where the 4xx error codes 400 through 418 live.
Nearby numbers
How to read this page
The factor list shows every way 404 splits into equal whole-number groups — 6 divisors in total. The prime factorisation is the compact form of that same information, and the base conversions restate 404 for contexts that do not use decimal.
Percentage calculator · Fraction calculator · Browse Number Explorer