1,681
1,681 is a composite number, odd, a calendar year.
Notable events — 1681 AD
- Mar 4 Charles II grants William Penn the charter for Pennsylvania.
- Jul 21 Russia and the Ottomans sign the Treaty of Bakhchisarai.
- Sep 30 French troops occupy Strasbourg.
Events compiled from Wikipedia ↗ · Licensed CC BY-SA 4.0
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, 1681
- Ended on
-
Wednesday
December 31, 1681
- Friday the 13ths
-
1
One Friday the 13th this year.
- Easter Sunday
-
April 6
Sunday, April 6, 1681
- Decade
-
1680s
1680–1689
- Century
-
17th century
1601–1700
- Millennium
-
2nd millennium
1001–2000
- Years ago
-
345
345 years before 2026.
In other calendars
- Hebrew
-
5441 / 5442 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
1091 / 1092 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Metal zodiac:Rooster
Sexagenary cycle position 58 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
2224 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
1059 / 1060 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
1673 / 1674 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
1603 / 1602 Saka
Indian national calendar; year starts in March.
Properties
- Parity
- Odd
- Digit count
- 4
- Digit sum
- 16
- Digit product
- 48
- Digital root
- 7
- Palindrome
- No
- Bit width
- 11 bits
- Reversed
- 1,861
- Flips to (rotate 180°)
- 1,891
- Recamán's sequence
- a(830) = 1,681
- Square (n²)
- 2,825,761
- Cube (n³)
- 4,750,104,241
- Square root (√n)
- 41
- Divisor count
- 3
- σ(n) — sum of divisors
- 1,723
- φ(n) — Euler's totient
- 1,640
- Sum of prime factors
- 82
Primality
Prime factorization: 41 2
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- one thousand six hundred eighty-one
- Ordinal
- 1681st
- Roman numeral
- MDCLXXXI
- Binary
- 11010010001
- Octal
- 3221
- Hexadecimal
- 0x691
- Base64
- BpE=
- One's complement
- 63,854 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹 𒁹
- Egyptian hieroglyphic
- 𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
- Greek (Milesian)
- ͵αχπαʹ
- Mayan (base 20)
- 𝋤·𝋤·𝋡
- Chinese
- 一千六百八十一
- Chinese (financial)
- 壹仟陸佰捌拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 1,681 = 8
- e — Euler's number (e)
- Digit 1,681 = 5
- φ — Golden ratio (φ)
- Digit 1,681 = 5
- √2 — Pythagoras's (√2)
- Digit 1,681 = 6
- ln 2 — Natural log of 2
- Digit 1,681 = 2
- γ — Euler-Mascheroni (γ)
- Digit 1,681 = 1
Also seen as
UTF-8 encoding: DA 91 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.6.145.
- Address
- 0.0.6.145
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.6.145
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 1681 first appears in π at position 17,200 of the decimal expansion (the 17,200ordinal-suffix:th digit after the integer 3).
Search range: the first 1,000,000 fractional digits of π. Any 6-digit-or-shorter string is virtually guaranteed to appear in there — the more interesting signal is the position.