39
39 is a composite number, odd, a calendar year.
39 (thirty-nine) is an odd 2-digit number. It is a composite number with 4 divisors, and factors as 3 × 13. Written other ways, in Roman numerals it is XXXIX and in binary, 100111.
Interestingness
Historical context — 39 AD
Calendar year
AD 39 (XXXIX) was a common year starting on Thursday of the Julian calendar.
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Historical context — 39 BC
Calendar year
Year 39 BC was either a common year starting on Friday, Saturday or Sunday or a leap year starting on Saturday of the Julian calendar and a common year starting on Saturday of the Proleptic Julian 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
-
Saturday
January 1, 39
- Ended on
-
Saturday
December 31, 39
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
30s
30–39
- Century
-
1st century
1–100
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,987
1987 years before 2026.
In other calendars
- Hebrew
-
3799 / 3800 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Earth zodiac:Pig
Sexagenary cycle position 36 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
582 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
31 / 32 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
-39 / -40 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 3 × 13
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√39 = [6; (4, 12)]
Period length 2 — the block in parentheses repeats forever.
Representations
- In words
- thirty-nine
- Ordinal
- 39th
- Roman numeral
- XXXIX
- Binary
- 100111
- Octal
- 47
- Hexadecimal
- 0x27
- Base64
- Jw==
- One's complement
- 216 (8-bit)
- Scientific notation
- 3.9 × 10¹
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- λθʹ
- Mayan (base 20)
- 𝋡·𝋳
- Chinese
- 三十九
- Chinese (financial)
- 參拾玖
Digit at this position in famous constants
- π — Pi (π)
- Digit 39 = 9
- e — Euler's number (e)
- Digit 39 = 5
- φ — Golden ratio (φ)
- Digit 39 = 2
- √2 — Pythagoras's (√2)
- Digit 39 = 6
- ln 2 — Natural log of 2
- Digit 39 = 7
- γ — Euler-Mascheroni (γ)
- Digit 39 = 4
Also seen as
As an ASCII codepoint, 39 is '. Printable ASCII character '.
As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.39.
- Address
- 0.0.0.39
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.0.39
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Matches numbered highway designation:
- I-39 — Normal, IL to Wausau, WI.
Heard as a frequency, 39 Hz is closest to:
- Concert pitch (A4 = 440 Hz): D♯1 (38.9 Hz, +5¢)
- Scientific pitch (C4 = 256 Hz): D♯1 (38.1 Hz, +42¢)
- Baroque pitch (A4 = 415 Hz): E1 (38.9 Hz, +6¢)
As a MIDI note number, 39 is D♯2 (77.8 Hz at concert pitch). (very low — many laptop and phone speakers can't reproduce it)
On the periodic table, atomic number 39 is Yttrium (Y) — period 5.
Related reading
- Babylonian numerals — The base-60 cuneiform system that gave us 60 minutes, 60 seconds, and 360°.