71
71 is a prime, odd, a calendar year.
71 (seventy-one) is an odd 2-digit number. It is a prime number — divisible only by 1 and itself. Written other ways, in Roman numerals it is LXXI and in binary, 1000111.
Interestingness
Historical context — 71 AD
Calendar year
AD 71 (LXXI) was a common year starting on Tuesday of the Julian calendar.
Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 Read the full article on Wikipedia →
Historical context — 71 BC
Calendar year
Year 71 BC was a year of the pre-Julian Roman calendar.
Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 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
-
53
Long year: contains 53 ISO weeks.
- Started on
-
Thursday
January 1, 71
- Ended on
-
Thursday
December 31, 71
- Friday the 13ths
-
3
3 Friday the 13ths this year.
- Decade
-
70s
70–79
- Century
-
1st century
1–100
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,955
1955 years before 2026.
In other calendars
- Hebrew
-
3831 / 3832 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Metal zodiac:Goat
Sexagenary cycle position 8 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
614 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
63 / 64 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
-7 / -8 Saka
Indian national calendar; year starts in March.
Properties
Primality
71 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√71 = [8; (2, 2, 1, 7, 1, 2, 2, 16)]
Period length 8 — the block in parentheses repeats forever.
Representations
- In words
- seventy-one
- Ordinal
- 71st
- Roman numeral
- LXXI
- Binary
- 1000111
- Octal
- 107
- Hexadecimal
- 0x47
- Base64
- Rw==
- One's complement
- 184 (8-bit)
- Scientific notation
- 7.1 × 10¹
- As a duration
- 71 s = 1 minute, 11 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹 𒌋𒁹
- Egyptian hieroglyphic
- 𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- οαʹ
- Mayan (base 20)
- 𝋣·𝋫
- Chinese
- 七十一
- Chinese (financial)
- 柒拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 71 = 4
- e — Euler's number (e)
- Digit 71 = 6
- φ — Golden ratio (φ)
- Digit 71 = 4
- √2 — Pythagoras's (√2)
- Digit 71 = 4
- ln 2 — Natural log of 2
- Digit 71 = 6
- γ — Euler-Mascheroni (γ)
- Digit 71 = 7
Also seen as
As an ASCII codepoint, 71 is G. Printable ASCII character G.
As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.71.
- Address
- 0.0.0.71
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.0.71
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Matches numbered highway designation:
- I-71 — Louisville, KY to Cleveland, OH.
Heard as a frequency, 71 Hz is closest to:
- Concert pitch (A4 = 440 Hz): C♯2 (69.3 Hz, +42¢)
- Scientific pitch (C4 = 256 Hz): D2 (71.8 Hz, -20¢)
- Baroque pitch (A4 = 415 Hz): D2 (69.2 Hz, +43¢)
As a MIDI note number, 71 is B4 (493.9 Hz at concert pitch).
On the periodic table, atomic number 71 is Lutetium (Lu) — period 6.
Related reading
- Prime numbers — The building blocks of arithmetic: what primes are, why they matter, and how we find them.
- Mayan numerals — Vigesimal dots-and-bars with a shell zero — one of the earliest true zeros.