993
Port 993 carries IMAP over TLS — encrypted mail reading.
- Odd
- Composite
Where 993 fits
Why 993 is special
993 pairs with 143 the way 443 pairs with 80: same protocol, encrypted from the first byte rather than upgraded mid-conversation. Mail clients default to it now, which is why a mail password is no longer readable by anyone sharing the network.
Factors & digit properties
- Divisors (4)
- 1, 3, 331, 993
- Prime factorisation
- 3 × 331
- Digit sum
- 21
- Digital root
- 3
Representations
- Decimal
- 993
- Binary
- 1111100001
- Octal
- 1741
- Hexadecimal
- 3e1
- Roman numeral
- CMXCIII
- Scientific notation
- 9.930 × 10^2
Other mathematical patterns
- Deficient number
- Semiprime
- Lucky number (mathematical sieve)
Related numbers & connections
Both are the TLS-from-the-first-byte version of an older plaintext port. The pattern — a separate port rather than an in-band upgrade — repeats across the protocols that moved to encryption early.
View 443 →Other connections
- is associated with443
why?
Strength 0.50, confidence "high".
Technology & computing
993 is to 143 what 443 is to 80 — the same protocol wrapped in TLS from the start rather than upgraded mid-conversation. Clients default to it now, which is why a mail password is no longer readable by anyone sharing a network.
DocumentedTechnology & computing
Common questions
Is 993 a prime number?
No, 993 is not prime.
What are the factors of 993?
The factors of 993 are 1, 3, 331, 993.
What is 993 in Roman numerals?
993 in Roman numerals is CMXCIII.
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