Number

621

621 is a composite number, odd, a calendar year.

Arithmetic Number Deficient Number Descending Digits Evil Number Harshad / Niven Recamán's Sequence Year

Historical context — 621 AD

Calendar year

Year 621 (DCXXI) was a common year starting on Thursday of the Julian calendar.

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Historical context — 621 BC

Calendar year

The year 621 BC was a year of the pre-Julian Roman calendar.

Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 · English fallback Read the full article on Wikipedia →

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, 621
Ended on: Monday
December 31, 621
Friday the 13ths: 2
2 Friday the 13ths this year.
Decade: 620s
620–629
Century: 7th century
601–700
Millennium: 1st millennium
1–1000
Years ago: 1,405
1405 years before 2026.

In other calendars

Hebrew: 4381 / 4382 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Metal zodiac:Snake
Sexagenary cycle position 18 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 1164 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 613 / 614 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 543 / 542 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 9
Digit product: 12
Digital root: 9
Palindrome: No
Bit width: 10 bits
Reversed: 126
Recamán's sequence: a(8,898) = 621
Square (n²): 385,641
Cube (n³): 239,483,061
Divisor count: 8
σ(n) — sum of divisors: 960
φ(n) — Euler's totient: 396
Sum of prime factors: 32

Primality

Prime factorization: 3 ³ × 23

Nearest primes: 619 (−2) · 631 (+10)

Divisors & multiples

All divisors (8)

1 · 3 · 9 · 23 · 27 · 69 · 207 · 621

Aliquot sum (sum of proper divisors): 339

Factor pairs (a × b = 621)

1 × 621

3 × 207

9 × 69

23 × 27

First multiples

621 · 1,242 (double) · 1,863 · 2,484 · 3,105 · 3,726 · 4,347 · 4,968 · 5,589 · 6,210

Sums & aliquot sequence

As consecutive integers: 310 + 311 206 + 207 + 208 101 + 102 + 103 + 104 + 105 + 106 65 + 66 + … + 73

Aliquot sequence: 621 → 339 → 117 → 65 → 19 → 1 → 0 — terminates at zero

Representations

In words: six hundred twenty-one
Ordinal: 621st
Roman numeral: DCXXI
Binary: 1001101101
Octal: 1155
Hexadecimal: 0x26D
Base64: Am0=
One's complement: 64,914 (16-bit)

In other bases

ternary (3) 212000

quaternary (4) 21231

quinary (5) 4441

senary (6) 2513

septenary (7) 1545

nonary (9) 760

undecimal (11) 515

duodecimal (12) 439

tridecimal (13) 38a

tetradecimal (14) 325

pentadecimal (15) 2b6

Historical numeral systems

Babylonian (base 60): 𒌋 𒌋𒌋𒁹
Egyptian hieroglyphic: 𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓏺
Greek (Milesian): χκαʹ
Mayan (base 20): 𝋡·𝋫·𝋡
Chinese: 六百二十一
Chinese (financial): 陸佰貳拾壹

In other modern scripts

Eastern Arabic ٦٢١ Devanagari ६२१ Bengali ৬২১ Tamil ௬௨௧ Thai ๖๒๑ Tibetan ༦༢༡ Khmer ៦២១ Lao ໖໒໑ Burmese ၆၂၁

Digit at this position in famous constants

π — Pi (π): Digit 621 = 2
e — Euler's number (e): Digit 621 = 9
φ — Golden ratio (φ): Digit 621 = 4
√2 — Pythagoras's (√2): Digit 621 = 0
ln 2 — Natural log of 2: Digit 621 = 5
γ — Euler-Mascheroni (γ): Digit 621 = 2

Also seen as

Unicode codepoint

Latin Small Letter L With Retroflex Hook

U+026D

Lowercase letter (Ll)

UTF-8 encoding: C9 AD (2 bytes).

Lookup U+026D on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#00026D

RGB(0, 2, 109)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.109.

Address: 0.0.2.109
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.2.109

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