990
990 is a composite number, even, a calendar year.
Historical context — 990 AD
Calendar year
Year 990 (CMXC) was a common year starting on Wednesday of the Julian calendar.
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Historical context — 990 BC
Decade
The 990s BC is a decade that lasted from 999 BC to 990 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
-
Friday
January 1, 990
- Ended on
-
Friday
December 31, 990
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
990s
990–999
- Century
-
10th century
901–1000
- Millennium
-
1st millennium
1–1000
- Years ago
-
1,036
1036 years before 2026.
In other calendars
- Hebrew
-
4750 / 4751 AM
Rosh Hashanah falls in September/October.
- Islamic Hijri
-
379 / 380 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
-
1533 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Persian Solar Hijri
-
368 / 369 SH
Iranian calendar; Nowruz (new year) falls on the spring equinox.
- Ethiopian
-
982 / 983 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
912 / 911 Saka
Indian national calendar; year starts in March.
Properties
- Parity
- Even
- Digit count
- 3
- Digit sum
- 18
- Digit product
- 0
- Digital root
- 9
- Palindrome
- No
- Bit width
- 10 bits
- Reversed
- 99
- Flips to (rotate 180°)
- 66
- Recamán's sequence
- a(4,439) = 990
- Square (n²)
- 980,100
- Cube (n³)
- 970,299,000
- Divisor count
- 24
- σ(n) — sum of divisors
- 2,808
- φ(n) — Euler's totient
- 240
- Sum of prime factors
- 24
Primality
Prime factorization: 2 × 3 2 × 5 × 11
Divisors & multiples
Sums & aliquot sequence
Representations
- In words
- nine hundred ninety
- Ordinal
- 990th
- Roman numeral
- CMXC
- Binary
- 1111011110
- Octal
- 1736
- Hexadecimal
- 0x3DE
- Base64
- A94=
- One's complement
- 64,545 (16-bit)
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒁹𒁹𒁹𒁹𒁹𒁹 𒌋𒌋𒌋
- Egyptian hieroglyphic
- 𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓎆
- Greek (Milesian)
- ϡϟʹ
- Mayan (base 20)
- 𝋢·𝋩·𝋪
- Chinese
- 九百九十
- Chinese (financial)
- 玖佰玖拾
Digit at this position in famous constants
- π — Pi (π)
- Digit 990 = 0
- e — Euler's number (e)
- Digit 990 = 8
- φ — Golden ratio (φ)
- Digit 990 = 2
- √2 — Pythagoras's (√2)
- Digit 990 = 2
- ln 2 — Natural log of 2
- Digit 990 = 7
- γ — Euler-Mascheroni (γ)
- Digit 990 = 2
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 990, here are decompositions:
- 7 + 983 = 990
- 13 + 977 = 990
- 19 + 971 = 990
- 23 + 967 = 990
- 37 + 953 = 990
- 43 + 947 = 990
- 53 + 937 = 990
- 61 + 929 = 990
Showing the first eight; more decompositions exist.
UTF-8 encoding: CF 9E (2 bytes).
TCP/UDP port 990 is the well-known port for FTPS — FTP over TLS — control channel.
As an unsigned 32-bit integer, this is the IPv4 address 0.0.3.222.
- Address
- 0.0.3.222
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.3.222
Unspecified address (0.0.0.0/8) — "this network" placeholder.
This passes the ABA routing number checksum and matches the Federal Reserve numbering scheme.
Banks operate many routing numbers per state and division; an unmatched checksum-valid number can still be a real RTN at a smaller institution.