1,621
1,621 is a prime, odd, a calendar year.
1,621 (one thousand six hundred twenty-one) is an odd 4-digit number. It is a prime number — divisible only by 1 and itself. Written other ways, in Roman numerals it is MDCXXI and in binary, 11001010101.
Interestingness
Notable events — 1621 AD
- Nov 4 Plymouth Colony celebrates an early harvest feast remembered as the first Thanksgiving.
- Mar 17 Cornelis Drebbel demonstrates an early submarine on the Thames.
- Jul 28 Frederick Henry becomes stadtholder of the Dutch Republic.
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
-
Friday
January 1, 1621
- Ended on
-
Friday
December 31, 1621
- Friday the 13ths
-
1
One Friday the 13th this year.
- Easter Sunday
-
April 11
Sunday, April 11, 1621
- Decade
-
1620s
1620–1629
- Century
-
17th century
1601–1700
- Millennium
-
2nd millennium
1001–2000
- Years ago
-
405
405 years before 2026.
In other calendars
- Hebrew
-
5381 / 5382 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
1030 / 1031 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
-
2164 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
999 / 1000 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
1613 / 1614 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
1543 / 1542 Saka
Indian national calendar; year starts in March.
Properties
Primality
1,621 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√1,621 = [40; (3, 1, 4, 1, 1, 1, 1, 1, 1, 2, 3, 1, 5, 1, 15, 3, 1, 26, 11, 2, 6, 1, 5, 3, …)]
Representations
- In words
- one thousand six hundred twenty-one
- Ordinal
- 1621st
- Roman numeral
- MDCXXI
- Binary
- 11001010101
- Octal
- 3125
- Hexadecimal
- 0x655
- Base64
- BlU=
- One's complement
- 63,914 (16-bit)
- Scientific notation
- 1.621 × 10³
- As a duration
- 1,621 s = 27 minutes, 1 second
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹 𒁹
- Egyptian hieroglyphic
- 𓆼𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓏺
- Greek (Milesian)
- ͵αχκαʹ
- Mayan (base 20)
- 𝋤·𝋡·𝋡
- Chinese
- 一千六百二十一
- Chinese (financial)
- 壹仟陸佰貳拾壹
Digit at this position in famous constants
- π — Pi (π)
- Digit 1,621 = 2
- e — Euler's number (e)
- Digit 1,621 = 6
- φ — Golden ratio (φ)
- Digit 1,621 = 7
- √2 — Pythagoras's (√2)
- Digit 1,621 = 5
- ln 2 — Natural log of 2
- Digit 1,621 = 6
- γ — Euler-Mascheroni (γ)
- Digit 1,621 = 4
Also seen as
UTF-8 encoding: D9 95 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.6.85.
- Address
- 0.0.6.85
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.6.85
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Heard as a frequency, 1,621 Hz is closest to:
- Concert pitch (A4 = 440 Hz): G♯6 (1661.2 Hz, -42¢)
- Scientific pitch (C4 = 256 Hz): G♯6 (1625.5 Hz, -5¢)
- Baroque pitch (A4 = 415 Hz): A6 (1660 Hz, -41¢)
The digit sequence 1621 first appears in π at position 32,910 of the decimal expansion (the 32,910ordinal-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.
Related reading
- Prime numbers — The building blocks of arithmetic: what primes are, why they matter, and how we find them.
- Egyptian hieroglyphic numerals — Seven hieroglyphs for every power of ten, from a single stroke to a million.