402
402 is the HTTP status code Payment Required — reserved in 1997 for a digital payment system that never arrived.
- Even
- Composite
Where 402 fits
Why 402 is special
402 is a placeholder that has been waiting for its use case for nearly thirty years. It was set aside for some future web-native micropayment scheme, and because no standard one emerged, the code remains formally reserved. Some APIs now use it for billing failures, which is a pragmatic borrowing rather than the intended meaning.
Not just a mathematical number
402is also used in ways where ordinary arithmetic doesn't apply — each listed below with what genuinely does and doesn't follow from it.
- Mathematical number
A genuine quantity — its mathematical properties (prime, square, factors, and so on) are real facts about it.
A genuine quantity that ordinary arithmetic applies to — it can be prime, even, a perfect square, added to another number meaningfully, and so on.
- Code
Also used as a code — HTTP status codes.
An assigned identifier from a fixed registry or standard — its digits don't represent an amount, and arithmetic on it is meaningless (HTTP status 404 + 1 is not a 'better' status; it's a different, unrelated code).
Factors & digit properties
- Divisors (8)
- 1, 2, 3, 6, 67, 134, 201, 402
- Prime factorisation
- 2 × 3 × 67
- Digit sum
- 6
- Digital root
- 6
Representations
- Decimal
- 402
- Binary
- 110010010
- Octal
- 622
- Hexadecimal
- 192
- Roman numeral
- CDII
- Scientific notation
- 4.020 × 10^2
Other mathematical patterns
- Abundant number
- Harshad (Niven) number
Related numbers & connections
402 has been reserved for a web-native payment mechanism since the 1990s.
Numbers Around Us
- appears inHTTP status codes
why?
Strength 0.50, confidence "high".
Technology & computing
The Cessna 402 was widely used by commuter airlines and air taxi operators, carrying up to nine passengers on routes too thin for larger equipment.
DocumentedTechnology & computingGeography: United StatesPeriod: 1966–1985402 was set aside in the 1990s for a web-native payment mechanism that never standardised. It is the only status code in the core specification still formally reserved, and its persistence is a small record of an expectation the web had about itself: that paying for a page would be a protocol feature rather than a platform's business.
DocumentedTechnology & computingPeriod: 1997 – present
Common questions
Is 402 a prime number?
No, 402 is not prime.
What are the factors of 402?
The factors of 402 are 1, 2, 3, 6, 67, 134, 201, 402.
What is 402 in Roman numerals?
402 in Roman numerals is CDII.
About this page's data
Mathematical facts:computed directly from the number's value — nothing to source or verify externally.
Contextual records: 2 reviewer-confirmed records, sourced and reviewed before publication.
Last reviewed: 3 August 2026