1,644
1,644 is a composite number, even, a calendar year.
Notable events — 1644 AD
- Apr 25 Beijing falls to rebels; the Ming dynasty ends with the emperor's suicide.
- Jul 2 Parliamentarians win at Marston Moor.
- Jun 6 The Manchu Qing dynasty enters Beijing.
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
-
Friday
January 1, 1644
- Ended on
-
Saturday
December 31, 1644
- Friday the 13ths
-
1
One Friday the 13th this year.
- Easter Sunday
-
March 27
Sunday, March 27, 1644
- Decade
-
1640s
1640–1649
- Century
-
17th century
1601–1700
- Millennium
-
2nd millennium
1001–2000
- Years ago
-
382
382 years before 2026.
In other calendars
- Hebrew
-
5404 / 5405 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
1053 / 1054 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Wood zodiac:Monkey
Sexagenary cycle position 21 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
2187 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
1022 / 1023 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
1636 / 1637 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
1566 / 1565 Saka
Indian national calendar; year starts in March.
Properties
- Parity
- Even
- Digit count
- 4
- Digit sum
- 15
- Digit product
- 96
- Digital root
- 6
- Palindrome
- No
- Bit width
- 11 bits
- Reversed
- 4,461
- Recamán's sequence
- a(1,028) = 1,644
- Square (n²)
- 2,702,736
- Cube (n³)
- 4,443,297,984
- Divisor count
- 12
- σ(n) — sum of divisors
- 3,864
- φ(n) — Euler's totient
- 544
- Sum of prime factors
- 144
Primality
Prime factorization: 2 2 × 3 × 137
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- one thousand six hundred forty-four
- Ordinal
- 1644th
- Roman numeral
- MDCXLIV
- Binary
- 11001101100
- Octal
- 3154
- Hexadecimal
- 0x66C
- Base64
- Bmw=
- One's complement
- 63,891 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺
- Greek (Milesian)
- ͵αχμδʹ
- Mayan (base 20)
- 𝋤·𝋢·𝋤
- Chinese
- 一千六百四十四
- Chinese (financial)
- 壹仟陸佰肆拾肆
Digit at this position in famous constants
- π — Pi (π)
- Digit 1,644 = 7
- e — Euler's number (e)
- Digit 1,644 = 3
- φ — Golden ratio (φ)
- Digit 1,644 = 1
- √2 — Pythagoras's (√2)
- Digit 1,644 = 5
- ln 2 — Natural log of 2
- Digit 1,644 = 8
- γ — Euler-Mascheroni (γ)
- Digit 1,644 = 0
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 1644, here are decompositions:
- 7 + 1637 = 1644
- 17 + 1627 = 1644
- 23 + 1621 = 1644
- 31 + 1613 = 1644
- 37 + 1607 = 1644
- 43 + 1601 = 1644
- 47 + 1597 = 1644
- 61 + 1583 = 1644
Showing the first eight; more decompositions exist.
UTF-8 encoding: D9 AC (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.6.108.
- Address
- 0.0.6.108
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.6.108
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The digit sequence 1644 first appears in π at position 3,370 of the decimal expansion (the 3,370ordinal-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.