Number

1,691

1,691 is a composite number, odd, a calendar year.

Arithmetic Number Deficient Number Flippable Odious Number Pernicious Number Recamán's Sequence Semiprime Squarefree Strobogrammatic Year

Notable events — 1691 AD

Oct 3 The Treaty of Limerick ends Williamite War in Ireland.
Aug 19 Habsburg forces win at Szalánkemén against the Ottomans.
Apr 29 The Massachusetts charter is restored as a royal colony.

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: Monday
January 1, 1691
Ended on: Monday
December 31, 1691
Friday the 13ths: 2
2 Friday the 13ths this year.
Easter Sunday: April 15
Sunday, April 15, 1691
Decade: 1690s
1690–1699
Century: 17th century
1601–1700
Millennium: 2nd millennium
1001–2000
Years ago: 335
335 years before 2026.

In other calendars

Hebrew: 5451 / 5452 AM
Rosh Hashanah falls in September/October.
Islamic Hijri: 1102 / 1103 AH
Lunar calendar; year spans differ from Gregorian.
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: 2234 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Persian Solar Hijri: 1069 / 1070 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
Ethiopian: 1683 / 1684 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 1613 / 1612 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 4
Digit sum: 17
Digit product: 54
Digital root: 8
Palindrome: No
Bit width: 11 bits
Reversed: 1,961
Recamán's sequence: a(950) = 1,691
Square (n²): 2,859,481
Cube (n³): 4,835,382,371
Divisor count: 4
σ(n) — sum of divisors: 1,800
φ(n) — Euler's totient: 1,584
Sum of prime factors: 108

Primality

Prime factorization: 19 × 89

Nearest primes: 1,669 (−22) · 1,693 (+2)

Divisors & multiples

All divisors (4)

1 · 19 · 89 · 1691

Aliquot sum (sum of proper divisors): 109

Factor pairs (a × b = 1,691)

1 × 1691

19 × 89

First multiples

1,691 · 3,382 (double) · 5,073 · 6,764 · 8,455 · 10,146 · 11,837 · 13,528 · 15,219 · 16,910

Sums & aliquot sequence

As consecutive integers: 845 + 846 80 + 81 + … + 98 26 + 27 + … + 63

Aliquot sequence: 1,691 → 109 → 1 → 0 — terminates at zero

Representations

In words: one thousand six hundred ninety-one
Ordinal: 1691st
Roman numeral: MDCXCI
Binary: 11010011011
Octal: 3233
Hexadecimal: 0x69B
Base64: Bps=
One's complement: 63,844 (16-bit)

In other bases

ternary (3) 2022122

quaternary (4) 122123

quinary (5) 23231

senary (6) 11455

septenary (7) 4634

nonary (9) 2278

undecimal (11) 12a8

duodecimal (12) b8b

tridecimal (13) a01

tetradecimal (14) 88b

pentadecimal (15) 77b

Historical numeral systems

Babylonian (base 60): 𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹 𒌋𒁹
Egyptian hieroglyphic: 𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺
Greek (Milesian): ͵αχϟαʹ
Mayan (base 20): 𝋤·𝋤·𝋫
Chinese: 一千六百九十一
Chinese (financial): 壹仟陸佰玖拾壹

In other modern scripts

Eastern Arabic ١٦٩١ Devanagari १६९१ Bengali ১৬৯১ Tamil ௧௬௯௧ Thai ๑๖๙๑ Tibetan ༡༦༩༡ Khmer ១៦៩១ Lao ໑໖໙໑ Burmese ၁၆၉၁

Digit at this position in famous constants

π — Pi (π): Digit 1,691 = 9
e — Euler's number (e): Digit 1,691 = 8
φ — Golden ratio (φ): Digit 1,691 = 1
√2 — Pythagoras's (√2): Digit 1,691 = 2
ln 2 — Natural log of 2: Digit 1,691 = 2
γ — Euler-Mascheroni (γ): Digit 1,691 = 1

Also seen as

Unicode codepoint

Arabic Letter Seen With Three Dots Below

U+069B

Other letter (Lo)

UTF-8 encoding: DA 9B (2 bytes).

Lookup U+069B on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#00069B

RGB(0, 6, 155)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.6.155.

Address: 0.0.6.155
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.6.155

Unspecified address (0.0.0.0/8) — "this network" placeholder.

Position in π

The digit sequence 1691 first appears in π at position 20,688 of the decimal expansion (the 20,688ordinal-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.

Look up 1691 on Pi Search ↗