1,668
1,668 is a composite number, even, a calendar year.
Notable events — 1668 AD
- May 2 The Treaty of Aix-la-Chapelle ends the War of Devolution.
- Feb 13 Spain recognizes Portuguese independence by the Treaty of Lisbon.
- Nov 25 The Triple Alliance of the Dutch, English, and Swedes counters France.
Events compiled from Wikipedia ↗ · Licensed CC BY-SA 4.0
Year facts
- Year type
-
Leap year
Divisible by 4 and not by 100; February has 29 days.
- Days in year
- 366
- ISO weeks
- 52
- Started on
-
Sunday
January 1, 1668
- Ended on
-
Monday
December 31, 1668
- Friday the 13ths
-
3
3 Friday the 13ths this year.
- Easter Sunday
-
April 1
Sunday, April 1, 1668
- Decade
-
1660s
1660–1669
- Century
-
17th century
1601–1700
- Millennium
-
2nd millennium
1001–2000
- Years ago
-
358
358 years before 2026.
In other calendars
- Hebrew
-
5428 / 5429 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
1078 / 1079 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Earth zodiac:Monkey
Sexagenary cycle position 45 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
2211 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
1046 / 1047 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
1660 / 1661 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
1590 / 1589 Saka
Indian national calendar; year starts in March.
Properties
- Parity
- Even
- Digit count
- 4
- Digit sum
- 21
- Digit product
- 288
- Digital root
- 3
- Palindrome
- No
- Bit width
- 11 bits
- Reversed
- 8,661
- Flips to (rotate 180°)
- 8,991
- Recamán's sequence
- a(804) = 1,668
- Square (n²)
- 2,782,224
- Cube (n³)
- 4,640,749,632
- Divisor count
- 12
- σ(n) — sum of divisors
- 3,920
- φ(n) — Euler's totient
- 552
- Sum of prime factors
- 146
Primality
Prime factorization: 2 2 × 3 × 139
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- one thousand six hundred sixty-eight
- Ordinal
- 1668th
- Roman numeral
- MDCLXVIII
- Binary
- 11010000100
- Octal
- 3204
- Hexadecimal
- 0x684
- Base64
- BoQ=
- One's complement
- 63,867 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- ͵αχξηʹ
- Mayan (base 20)
- 𝋤·𝋣·𝋨
- Chinese
- 一千六百六十八
- Chinese (financial)
- 壹仟陸佰陸拾捌
Digit at this position in famous constants
- π — Pi (π)
- Digit 1,668 = 3
- e — Euler's number (e)
- Digit 1,668 = 3
- φ — Golden ratio (φ)
- Digit 1,668 = 7
- √2 — Pythagoras's (√2)
- Digit 1,668 = 6
- ln 2 — Natural log of 2
- Digit 1,668 = 6
- γ — Euler-Mascheroni (γ)
- Digit 1,668 = 9
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 1668, here are decompositions:
- 5 + 1663 = 1668
- 11 + 1657 = 1668
- 31 + 1637 = 1668
- 41 + 1627 = 1668
- 47 + 1621 = 1668
- 59 + 1609 = 1668
- 61 + 1607 = 1668
- 67 + 1601 = 1668
Showing the first eight; more decompositions exist.
UTF-8 encoding: DA 84 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.6.132.
- Address
- 0.0.6.132
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.6.132
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 1668 first appears in π at position 4,128 of the decimal expansion (the 4,128ordinal-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.