Number

123

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

Arithmetic Number Ascending Digits Consecutive Digits Deficient Number Evil Number Lucas Recamán's Sequence Semiprime Squarefree Year

Historical context — 123 AD

Calendar year

Year 123 (CXXIII) was a common year starting on Thursday of the Julian calendar.

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Historical context — 123 BC

Calendar year

Year 123 BC was a year of the pre-Julian Roman calendar.

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

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, 123
Ended on: Friday
December 31, 123
Friday the 13ths: 1
One Friday the 13th this year.
Decade: 120s
120–129
Century: 2nd century
101–200
Millennium: 1st millennium
1–1000
Years ago: 1,903
1903 years before 2026.

In other calendars

Hebrew: 3883 / 3884 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Water zodiac:Pig
Sexagenary cycle position 60 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 666 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 115 / 116 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 45 / 44 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 6
Digit product: 6
Digital root: 6
Palindrome: No
Bit width: 7 bits
Reversed: 321
Recamán's sequence: a(154) = 123
Square (n²): 15,129
Cube (n³): 1,860,867
Divisor count: 4
σ(n) — sum of divisors: 168
φ(n) — Euler's totient: 80
Sum of prime factors: 44

Primality

Prime factorization: 3 × 41

Nearest primes: 113 (−10) · 127 (+4)

Divisors & multiples

All divisors (4)

1 · 3 · 41 · 123

Aliquot sum (sum of proper divisors): 45

Factor pairs (a × b = 123)

1 × 123

3 × 41

First multiples

123 · 246 (double) · 369 · 492 · 615 · 738 · 861 · 984 · 1,107 · 1,230

Sums & aliquot sequence

As consecutive integers: 61 + 62 40 + 41 + 42 18 + 19 + 20 + 21 + 22 + 23

Aliquot sequence: 123 → 45 → 33 → 15 → 9 → 4 → 3 → 1 → 0 — terminates at zero

Representations

In words: one hundred twenty-three
Ordinal: 123rd
Roman numeral: CXXIII
Binary: 1111011
Octal: 173
Hexadecimal: 0x7B
Base64: ew==
One's complement: 132 (8-bit)

In other bases

ternary (3) 11120

quaternary (4) 1323

quinary (5) 443

senary (6) 323

septenary (7) 234

nonary (9) 146

undecimal (11) 102

duodecimal (12) a3

tridecimal (13) 96

tetradecimal (14) 8b

pentadecimal (15) 83

Historical numeral systems

Babylonian (base 60): 𒁹𒁹 𒁹𒁹𒁹
Egyptian hieroglyphic: 𓍢𓎆𓎆𓏺𓏺𓏺
Greek (Milesian): ρκγʹ
Mayan (base 20): 𝋦·𝋣
Chinese: 一百二十三
Chinese (financial): 壹佰貳拾參

In other modern scripts

Eastern Arabic ١٢٣ Devanagari १२३ Bengali ১২৩ Tamil ௧௨௩ Thai ๑๒๓ Tibetan ༡༢༣ Khmer ១២៣ Lao ໑໒໓ Burmese ၁၂၃

Digit at this position in famous constants

π — Pi (π): Digit 123 = 9
e — Euler's number (e): Digit 123 = 1
φ — Golden ratio (φ): Digit 123 = 2
√2 — Pythagoras's (√2): Digit 123 = 2
ln 2 — Natural log of 2: Digit 123 = 8
γ — Euler-Mascheroni (γ): Digit 123 = 6

Also seen as

ASCII character

As an ASCII codepoint, 123 is {. Printable ASCII character {.

Network port

TCP/UDP port 123 is the well-known port for NTP — Network Time Protocol.

Hex color

#00007B

RGB(0, 0, 123)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.123.

Address: 0.0.0.123
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.123

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

Possible US bank routing number

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

Routing number

000000123

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 000000123 ↗