628
628 is a composite number, even, a calendar year.
628 (six hundred twenty-eight) is an even 3-digit number. It is a composite number with 6 divisors, and factors as 2² × 157. Written other ways, in Roman numerals it is DCXXVIII and in binary, 1001110100.
Interestingness
Historical context — 628 AD
Calendar year
Year 628 (DCXXVIII) was a leap year starting on Friday of the Julian calendar.
Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 Read the full article on Wikipedia →
Historical context — 628 BC
Calendar year
The year 628 BC was a year of the pre-Julian Roman calendar.
Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 Read the full article on Wikipedia →
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
-
Tuesday
January 1, 628
- Ended on
-
Wednesday
December 31, 628
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
620s
620–629
- Century
-
7th century
601–700
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,398
1398 years before 2026.
In other calendars
- Hebrew
-
4388 / 4389 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
6 / 7 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Earth zodiac:Rat
Sexagenary cycle position 25 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
1171 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
6 / 7 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
620 / 621 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
550 / 549 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 2 2 × 157
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√628 = [25; (16, 1, 2, 5, 4, 2, 1, 2, 2, 3, 1, 3, 12, 3, 1, 3, 2, 2, 1, 2, 4, 5, 2, 1, …)]
Period length 26 — the block in parentheses repeats forever.
Representations
- In words
- six hundred twenty-eight
- Ordinal
- 628th
- Roman numeral
- DCXXVIII
- Binary
- 1001110100
- Octal
- 1164
- Hexadecimal
- 0x274
- Base64
- AnQ=
- One's complement
- 64,907 (16-bit)
- Scientific notation
- 6.28 × 10²
- As a duration
- 628 s = 10 minutes, 28 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒌋 𒌋𒌋𒁹𒁹𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓏺𓏺𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- χκηʹ
- Mayan (base 20)
- 𝋡·𝋫·𝋨
- Chinese
- 六百二十八
- Chinese (financial)
- 陸佰貳拾捌
Digit at this position in famous constants
- π — Pi (π)
- Digit 628 = 1
- e — Euler's number (e)
- Digit 628 = 7
- φ — Golden ratio (φ)
- Digit 628 = 2
- √2 — Pythagoras's (√2)
- Digit 628 = 6
- ln 2 — Natural log of 2
- Digit 628 = 6
- γ — Euler-Mascheroni (γ)
- Digit 628 = 0
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 628, here are decompositions:
- 11 + 617 = 628
- 29 + 599 = 628
- 41 + 587 = 628
- 59 + 569 = 628
- 71 + 557 = 628
- 107 + 521 = 628
- 137 + 491 = 628
- 149 + 479 = 628
Showing the first eight; more decompositions exist.
UTF-8 encoding: C9 B4 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.116.
- Address
- 0.0.2.116
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.2.116
Unspecified address (0.0.0.0/8) — "this network" placeholder.
The number 628 is an active NANP area code (North American Numbering Plan).
- Primary area
- San Francisco
- Region
- California
- Country
- United States
Most NANP area codes have multiple overlays in dense regions; the primary area listed is the historic/largest population center for this code.
Heard as a frequency, 628 Hz is closest to:
- Concert pitch (A4 = 440 Hz): D♯5 (622.3 Hz, +16¢)
- Scientific pitch (C4 = 256 Hz): E5 (645.1 Hz, -46¢ — about midway to D♯5)
- Baroque pitch (A4 = 415 Hz): E5 (621.8 Hz, +17¢)
Related reading
- Egyptian hieroglyphic numerals — Seven hieroglyphs for every power of ten, from a single stroke to a million.