Number

155

155 is a composite number, odd, a calendar year.

Arithmetic Number Deficient Number Odious Number Pernicious Number Recamán's Sequence Semiprime Squarefree Year

Historical context — 155 AD

Calendar year

Year 155 (CLV) was a common year starting on Tuesday of the Julian calendar.

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Historical context — 155 BC

Calendar year

Year 155 BC was a year of the pre-Julian Roman calendar.

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Year facts

Year type: Common year
Standard 365-day year; not divisible by 4 (or divisible by 100 but not 400).
Days in year: 365
ISO weeks: 52
Started on: Wednesday
January 1, 155
Ended on: Wednesday
December 31, 155
Friday the 13ths: 1
One Friday the 13th this year.
Decade: 150s
150–159
Century: 2nd century
101–200
Millennium: 1st millennium
1–1000
Years ago: 1,871
1871 years before 2026.

In other calendars

Hebrew: 3915 / 3916 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Wood zodiac:Goat
Sexagenary cycle position 32 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 698 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 147 / 148 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 77 / 76 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 11
Digit product: 25
Digital root: 2
Palindrome: No
Bit width: 8 bits
Reversed: 551
Recamán's sequence: a(70) = 155
Square (n²): 24,025
Cube (n³): 3,723,875
Divisor count: 4
σ(n) — sum of divisors: 192
φ(n) — Euler's totient: 120
Sum of prime factors: 36

Primality

Prime factorization: 5 × 31

Nearest primes: 151 (−4) · 157 (+2)

Divisors & multiples

All divisors (4)

1 · 5 · 31 · 155

Aliquot sum (sum of proper divisors): 37

Factor pairs (a × b = 155)

1 × 155

5 × 31

First multiples

155 · 310 (double) · 465 · 620 · 775 · 930 · 1,085 · 1,240 · 1,395 · 1,550

Sums & aliquot sequence

As consecutive integers: 77 + 78 29 + 30 + 31 + 32 + 33 11 + 12 + … + 20

Aliquot sequence: 155 → 37 → 1 → 0 — terminates at zero

Representations

In words: one hundred fifty-five
Ordinal: 155th
Roman numeral: CLV
Binary: 10011011
Octal: 233
Hexadecimal: 0x9B
Base64: mw==
One's complement: 100 (8-bit)

In other bases

ternary (3) 12202

quaternary (4) 2123

quinary (5) 1110

senary (6) 415

septenary (7) 311

nonary (9) 182

undecimal (11) 131

duodecimal (12) 10b

tridecimal (13) bc

tetradecimal (14) b1

pentadecimal (15) a5

Historical numeral systems

Babylonian (base 60): 𒁹𒁹 𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓍢𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺
Greek (Milesian): ρνεʹ
Mayan (base 20): 𝋧·𝋯
Chinese: 一百五十五
Chinese (financial): 壹佰伍拾伍

In other modern scripts

Eastern Arabic ١٥٥ Devanagari १५५ Bengali ১৫৫ Tamil ௧௫௫ Thai ๑๕๕ Tibetan ༡༥༥ Khmer ១៥៥ Lao ໑໕໕ Burmese ၁၅၅

Digit at this position in famous constants

π — Pi (π): Digit 155 = 1
e — Euler's number (e): Digit 155 = 6
φ — Golden ratio (φ): Digit 155 = 3
√2 — Pythagoras's (√2): Digit 155 = 8
ln 2 — Natural log of 2: Digit 155 = 9
γ — Euler-Mascheroni (γ): Digit 155 = 5

Also seen as

Unicode codepoint

Control Sequence Introducer

U+009B

Control character (Cc)

UTF-8 encoding: C2 9B (2 bytes).

Lookup U+009B on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#00009B

RGB(0, 0, 155)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.155.

Address: 0.0.0.155
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.155

Unspecified address (0.0.0.0/8) — "this network" placeholder.