Number

55

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

Arithmetic Number Deficient Number Fibonacci Heptagonal Kaprekar Number Odious Number Palindrome Pernicious Number Recamán's Sequence Repdigit Semiprime Square Pyramidal Squarefree Triangular Year

Historical context — 55 AD

Calendar year

AD 55 (LV) was a common year starting on Wednesday of the Julian calendar.

Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 · English fallback Read the full article on Wikipedia →

Notable events — 55 BC

Aug 26 Julius Caesar makes his first expedition to Britain.

Events compiled from Wikipedia ↗ · Licensed CC BY-SA 4.0

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: Friday
January 1, 55
Ended on: Friday
December 31, 55
Friday the 13ths: 1
One Friday the 13th this year.
Decade: 50s
50–59
Century: 1st century
1–100
Millennium: 1st millennium
1–1000
Years ago: 1,971
1971 years before 2026.

In other calendars

Hebrew: 3815 / 3816 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Wood zodiac:Rabbit
Sexagenary cycle position 52 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 598 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 47 / 48 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): -23 / -24 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 2
Digit sum: 10
Digit product: 25
Digital root: 1
Palindrome: Yes
Bit width: 6 bits
Recamán's sequence: a(206) = 55
Square (n²): 3,025
Cube (n³): 166,375
Divisor count: 4
σ(n) — sum of divisors: 72
φ(n) — Euler's totient: 40
Sum of prime factors: 16

Primality

Prime factorization: 5 × 11

Nearest primes: 53 (−2) · 59 (+4)

Divisors & multiples

All divisors (4)

1 · 5 · 11 · 55

Aliquot sum (sum of proper divisors): 17

Factor pairs (a × b = 55)

1 × 55

5 × 11

First multiples

55 · 110 (double) · 165 · 220 · 275 · 330 · 385 · 440 · 495 · 550

Sums & aliquot sequence

As consecutive integers: 27 + 28 9 + 10 + 11 + 12 + 13 1 + 2 + … + 10

Aliquot sequence: 55 → 17 → 1 → 0 — terminates at zero

Representations

In words: fifty-five
Ordinal: 55th
Roman numeral: LV
Binary: 110111
Octal: 67
Hexadecimal: 0x37
Base64: Nw==
One's complement: 200 (8-bit)

In other bases

ternary (3) 2001

quaternary (4) 313

quinary (5) 210

senary (6) 131

septenary (7) 106

nonary (9) 61

undecimal (11) 50

duodecimal (12) 47

tridecimal (13) 43

tetradecimal (14) 3d

pentadecimal (15) 3a

Historical numeral systems

Babylonian (base 60): 𒌋𒌋𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺
Greek (Milesian): νεʹ
Mayan (base 20): 𝋢·𝋯
Chinese: 五十五
Chinese (financial): 伍拾伍

In other modern scripts

Eastern Arabic ٥٥ Devanagari ५५ Bengali ৫৫ Tamil ௫௫ Thai ๕๕ Tibetan ༥༥ Khmer ៥៥ Lao ໕໕ Burmese ၅၅

Digit at this position in famous constants

π — Pi (π): Digit 55 = 0
e — Euler's number (e): Digit 55 = 4
φ — Golden ratio (φ): Digit 55 = 2
√2 — Pythagoras's (√2): Digit 55 = 3
ln 2 — Natural log of 2: Digit 55 = 4
γ — Euler-Mascheroni (γ): Digit 55 = 8

Also seen as

ASCII character

As an ASCII codepoint, 55 is 7. Printable ASCII character 7.

Hex color

#000037

RGB(0, 0, 55)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.55.

Address: 0.0.0.55
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.55

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

US numbered highway

Matches numbered highway designation:

I-55 — LaPlace, LA to Chicago, IL.

Interstate 55 on Wikipedia ↗

Possible US bank routing number

This passes the ABA routing number checksum and matches the Federal Reserve numbering scheme.

Routing number

000000055

Federal Reserve

United States Government

Banks operate many routing numbers per state and division; an unmatched checksum-valid number can still be a real RTN at a smaller institution.

Look up on FedACH (official) ↗ Search Google for routing number 000000055 ↗