587
Port 587 is the mail submission port, used by a mail program to hand a message to its own server.
- Odd
- Prime
Where 587 fits
Why 587 is special
587 exists to separate two jobs that port 25 had confused: server-to-server relay and a user submitting new mail. Submission on 587 requires authentication, which is why providers can block outbound 25 to stop spam without breaking legitimate mail clients.
587 is part of
Factors & digit properties
- Divisors (2)
- 1, 587
- Prime factorisation
- 587
- Digit sum
- 20
- Digital root
- 2
Representations
- Decimal
- 587
- Binary
- 1001001011
- Octal
- 1113
- Hexadecimal
- 24b
- Roman numeral
- DLXXXVII
- Scientific notation
- 5.870 × 10^2
Other mathematical patterns
- Deficient number
- Safe prime
Related numbers & connections
25 relays mail between servers and 587 accepts new mail from a person. Splitting them is what lets a provider block outbound 25 to suppress spam without breaking ordinary mail clients.
View 25 →Technology & computing
Port 25 confused two jobs: servers relaying mail to each other, and a person sending new mail. 587 handles only the second and requires authentication, which is what lets providers block outbound 25 to suppress spam without breaking ordinary mail clients.
DocumentedTechnology & computing
Common questions
Is 587 a prime number?
Yes, 587 is prime — it has exactly two positive divisors: 1 and itself.
What are the factors of 587?
The factors of 587 are 1, 587.
What is 587 in Roman numerals?
587 in Roman numerals is DLXXXVII.
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