690
690 is a composite number, even, a calendar year.
Historical context — 690 AD
Calendar year
Year 690 (DCXC) was a common year starting on Saturday of the Julian calendar.
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Historical context — 690 BC
Decade
This article concerns the period 699 BC – 690 BC.
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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
-
Wednesday
January 1, 690
- Ended on
-
Wednesday
December 31, 690
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
690s
690–699
- Century
-
7th century
601–700
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,336
1336 years before 2026.
In other calendars
- Hebrew
-
4450 / 4451 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
70 / 71 AH
Lunar calendar; year spans differ from Gregorian.
- Chinese
-
Year of the zodiac:Metal zodiac:Tiger
Sexagenary cycle position 27 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
1233 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
68 / 69 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
682 / 683 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
612 / 611 Saka
Indian national calendar; year starts in March.
Properties
- Parity
- Even
- Digit count
- 3
- Digit sum
- 15
- Digit product
- 0
- Digital root
- 6
- Palindrome
- No
- Bit width
- 10 bits
- Reversed
- 96
- Flips to (rotate 180°)
- 69
- Recamán's sequence
- a(2,244) = 690
- Square (n²)
- 476,100
- Cube (n³)
- 328,509,000
- Divisor count
- 16
- σ(n) — sum of divisors
- 1,728
- φ(n) — Euler's totient
- 176
- Sum of prime factors
- 33
Primality
Prime factorization: 2 × 3 × 5 × 23
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- six hundred ninety
- Ordinal
- 690th
- Roman numeral
- DCXC
- Binary
- 1010110010
- Octal
- 1262
- Hexadecimal
- 0x2B2
- Base64
- ArI=
- One's complement
- 64,845 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒁹 𒌋𒌋𒌋
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆
- Greek (Milesian)
- χϟʹ
- Mayan (base 20)
- 𝋡·𝋮·𝋪
- Chinese
- 六百九十
- Chinese (financial)
- 陸佰玖拾
Digit at this position in famous constants
- π — Pi (π)
- Digit 690 = 7
- e — Euler's number (e)
- Digit 690 = 3
- φ — Golden ratio (φ)
- Digit 690 = 4
- √2 — Pythagoras's (√2)
- Digit 690 = 0
- ln 2 — Natural log of 2
- Digit 690 = 9
- γ — Euler-Mascheroni (γ)
- Digit 690 = 8
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 690, here are decompositions:
- 7 + 683 = 690
- 13 + 677 = 690
- 17 + 673 = 690
- 29 + 661 = 690
- 31 + 659 = 690
- 37 + 653 = 690
- 43 + 647 = 690
- 47 + 643 = 690
Showing the first eight; more decompositions exist.
UTF-8 encoding: CA B2 (2 bytes).
As an unsigned 32-bit integer, this is the IPv4 address 0.0.2.178.
- Address
- 0.0.2.178
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.2.178
Unspecified address (0.0.0.0/8) — "this network" placeholder.