138
138 is a composite number, even, a calendar year.
Historical context — 138 AD
Calendar year
Year 138 (CXXXVIII) was a common year starting on Tuesday of the Julian calendar.
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Historical context — 138 BC
Calendar year
Year 138 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, 138
- Ended on
-
Wednesday
December 31, 138
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
130s
130–139
- Century
-
2nd century
101–200
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,888
1888 years before 2026.
In other calendars
- Hebrew
-
3898 / 3899 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Earth zodiac:Tiger
Sexagenary cycle position 15 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
681 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
130 / 131 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
60 / 59 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 2 × 3 × 23
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- one hundred thirty-eight
- Ordinal
- 138th
- Roman numeral
- CXXXVIII
- Binary
- 10001010
- Octal
- 212
- Hexadecimal
- 0x8A
- Base64
- ig==
- One's complement
- 117 (8-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒁹𒁹 𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓍢𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- ρληʹ
- Mayan (base 20)
- 𝋦·𝋲
- Chinese
- 一百三十八
- Chinese (financial)
- 壹佰參拾捌
Digit at this position in famous constants
- π — Pi (π)
- Digit 138 = 3
- e — Euler's number (e)
- Digit 138 = 7
- φ — Golden ratio (φ)
- Digit 138 = 3
- √2 — Pythagoras's (√2)
- Digit 138 = 1
- ln 2 — Natural log of 2
- Digit 138 = 5
- γ — Euler-Mascheroni (γ)
- Digit 138 = 3
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 138, here are decompositions:
- 7 + 131 = 138
- 11 + 127 = 138
- 29 + 109 = 138
- 31 + 107 = 138
- 37 + 101 = 138
- 41 + 97 = 138
- 59 + 79 = 138
- 67 + 71 = 138
Showing the first eight; more decompositions exist.
UTF-8 encoding: C2 8A (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.138.
- Address
- 0.0.0.138
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.0.138
Unspecified address (0.0.0.0/8) — "this network" placeholder.