41
41 is a prime, odd, a calendar year.
41 (forty-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 XLI and in binary, 101001.
Interestingness
Historical context — 41 AD
Calendar year
AD 41 (XLI) was a common year starting on Sunday of the Julian calendar.
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Historical context — 41 BC
Calendar year
Year 41 BC was either a common year starting on Wednesday or Thursday or a leap year starting on Tuesday, Wednesday or Thursday of the Julian calendar and a leap year starting on Wednesday 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
-
Tuesday
January 1, 41
- Ended on
-
Tuesday
December 31, 41
- Friday the 13ths
-
2
2 Friday the 13ths this year.
- Decade
-
40s
40–49
- Century
-
1st century
1–100
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,985
1985 years before 2026.
In other calendars
- Hebrew
-
3801 / 3802 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Metal zodiac:Ox
Sexagenary cycle position 38 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
584 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
33 / 34 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
-37 / -38 Saka
Indian national calendar; year starts in March.
Properties
Primality
41 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√41 = [6; (2, 2, 12)]
Period length 3 — the block in parentheses repeats forever.
Representations
- In words
- forty-one
- Ordinal
- 41st
- Roman numeral
- XLI
- Binary
- 101001
- Octal
- 51
- Hexadecimal
- 0x29
- Base64
- KQ==
- One's complement
- 214 (8-bit)
- Scientific notation
- 4.1 × 10¹
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒌋𒌋𒁹
- Egyptian hieroglyphic
- 𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- μαʹ
- Mayan (base 20)
- 𝋢·𝋡
- Chinese
- 四十一
- Chinese (financial)
- 肆拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 41 = 1
- e — Euler's number (e)
- Digit 41 = 2
- φ — Golden ratio (φ)
- Digit 41 = 3
- √2 — Pythagoras's (√2)
- Digit 41 = 6
- ln 2 — Natural log of 2
- Digit 41 = 5
- γ — Euler-Mascheroni (γ)
- Digit 41 = 1
Also seen as
As an ASCII codepoint, 41 is ). Printable ASCII character ).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.41.
- Address
- 0.0.0.41
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.0.41
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Matches numbered highway designation:
- US 41 — Sault Ste. Marie, MI to Miami, FL.
Heard as a frequency, 41 Hz is closest to:
- Concert pitch (A4 = 440 Hz): E1 (41.2 Hz, -9¢)
- Scientific pitch (C4 = 256 Hz): E1 (40.3 Hz, +29¢)
- Baroque pitch (A4 = 415 Hz): F1 (41.2 Hz, -7¢)
As a MIDI note number, 41 is F2 (87.3 Hz at concert pitch). (very low — many laptop and phone speakers can't reproduce it)
On the periodic table, atomic number 41 is Niobium (Nb) — period 5.
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.