Number

1,621

1,621 is a prime, odd, a calendar year.

Arithmetic Number Chen Prime Deficient Number Evil Number Prime Pythagorean Prime Recamán's Sequence Sexy Prime Squarefree Twin Prime Year

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

Parity: Odd
Digit count: 4
Digit sum: 10
Digit product: 12
Digital root: 1
Palindrome: No
Bit width: 11 bits
Reversed: 1,261
Recamán's sequence: a(710) = 1,621
Square (n²): 2,627,641
Cube (n³): 4,259,406,061
Divisor count: 2
σ(n) — sum of divisors: 1,622
φ(n) — Euler's totient: 1,620

Primality

1,621 is prime. It has exactly two divisors: 1 and itself.

Divisors & multiples

All divisors (2)

1 · 1621

Aliquot sum (sum of proper divisors): 1

Factor pairs (a × b = 1,621)

1 × 1621

First multiples

1,621 · 3,242 (double) · 4,863 · 6,484 · 8,105 · 9,726 · 11,347 · 12,968 · 14,589 · 16,210

Sums & aliquot sequence

As a sum of two squares: 10² + 39²

As consecutive integers: 810 + 811

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)

In other bases

ternary (3) 2020001

quaternary (4) 121111

quinary (5) 22441

senary (6) 11301

septenary (7) 4504

nonary (9) 2201

undecimal (11) 1244

duodecimal (12) b31

tridecimal (13) 979

tetradecimal (14) 83b

pentadecimal (15) 731

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

In other modern scripts

Eastern Arabic ١٦٢١ Devanagari १६२१ Bengali ১৬২১ Tamil ௧௬௨௧ Thai ๑๖๒๑ Tibetan ༡༦༢༡ Khmer ១៦២១ Lao ໑໖໒໑ Burmese ၁၆၂၁

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

Prime neighborhood

Adjacent primes:

Previous prime: 1,619 (gap of 2)
Next prime: 1,627 (gap of 6)

Pair status: twin with 1619, sexy with 1627.

Unicode codepoint

Arabic Hamza Below

U+0655

Non-spacing mark (Mn)

UTF-8 encoding: D9 95 (2 bytes).

Lookup U+0655 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#000655

RGB(0, 6, 85)

IPv4 address

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.

Position in π

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.

Look up 1621 on Pi Search ↗