161
Port 161 carries SNMP, the protocol used to monitor network equipment.
- Odd
- Composite
Where 161 fits
Why 161 is special
Almost every switch, router and printer reports its status over SNMP. Older versions authenticate with a plain-text community string that defaults to 'public', which is why an exposed 161 has long been one of the easiest ways to map an organisation's internal network from outside.
161 is part of
Factors & digit properties
- Divisors (4)
- 1, 7, 23, 161
- Prime factorisation
- 7 × 23
- Digit sum
- 8
- Digital root
- 8
Representations
- Decimal
- 161
- Scientific notation
- 1.610 × 10^2
Roman numerals
C L X I
Binary
1 0 1 0 0 0 0 1
1 × 128 + 0 × 64 + 1 × 32 + 0 × 16 + 0 × 8 + 0 × 4 + 0 × 2 + 1 × 1 = 161
Octal
2 4 1
2 × 64 + 4 × 8 + 1 × 1 = 161
Hexadecimal
a 1
a × 16 + 1 × 1 = 161
Read as powers of two: 128 + 32 + 1 = 161.
In historical numeral systems
Egyptian
1 coil of rope, 6 hobbles, 1 stroke
1 × 100 + 6 × 10 + 1 × 1 = 161. The signs are simply repeated and added; where they sit on the line is a matter of layout, not value.
Babylonian
2 vertical wedges (sixties place), 4 corner wedges + 1 vertical wedge (units place)
2 × 60 + 41 = 161. Places are separated by a space on the tablet, with the higher place written first.
Greek (Ionic)
rho, then xi, then alpha, marked as a numeral
rho-xi-alpha + keraia
rho + xi + alpha written in descending order and added — the letters carry their values wherever they stand, so this is addition, not place value.
Hebrew numerals
qof, then samekh, then alef
qof-samekh-alef
qof (100) + samekh (60) + alef (1) = 161, written in descending order.
Maya
1 bar + 3 dots (upper, twenties place) over 1 dot (lower, units place)
8 × 20 + 1 = 161. Places stack vertically with the smallest at the bottom, so the upper group is worth twenty times the lower.
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
- Palindromic number
- Deficient number
- Semiprime
Related numbers & connections
SNMP polled and SNMP pushed. The polling interval on 161 is how long a fault can remain unnoticed, which is the entire argument for traps on 162.
View 162 →Technology & computing
SNMP v1 and v2c authenticate with a plain-text string, and the default is 'public'. An exposed port 161 has therefore been one of the simplest routes to a map of an organisation's internal equipment, which is why v3 exists and why so much kit still does not use it.
DocumentedTechnology & computing
Common questions
Is 161 a prime number?
No, 161 is not prime.
What are the factors of 161?
The factors of 161 are 1, 7, 23, 161.
What is 161 in Roman numerals?
161 in Roman numerals is CLXI.
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