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
- Scientific notation
- 5.870 × 10^2
Roman numerals
D L X X X V I I
Binary
1 0 0 1 0 0 1 0 1 1
1 × 512 + 0 × 256 + 0 × 128 + 1 × 64 + 0 × 32 + 0 × 16 + 1 × 8 + 0 × 4 + 1 × 2 + 1 × 1 = 587
Octal
1 1 1 3
1 × 512 + 1 × 64 + 1 × 8 + 3 × 1 = 587
Hexadecimal
2 4 b
2 × 256 + 4 × 16 + b × 1 = 587
Read as powers of two: 512 + 64 + 8 + 2 + 1 = 587.
In historical numeral systems
Egyptian
5 coils of rope, 8 hobbles, 7 strokes
5 × 100 + 8 × 10 + 7 × 1 = 587. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
9 vertical wedges (sixties place), 4 corner wedges + 7 vertical wedges (units place)
9 × 60 + 47 = 587. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
phi, then pi, then zeta, marked as a numeral
phi-pi-zeta + keraia
phi + pi + zeta written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
tav, then qof, then pe, then zayin
tav-qof-pe-zayin
tav (400) + qof (100) + pe (80) + zayin (7) = 587, written in descending order.
Systems that simply cannot reach this value are left out. Where a script needs a font most readers do not have, the reading is given instead of the glyphs — see number systems for each system in full.
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: 15 July 2026