22
22 is a composite number, even, a calendar year.
22 (twenty-two) is an even 2-digit number. It is a composite number with 4 divisors, and factors as 2 × 11. Its digits read the same forwards and backwards, so it is a palindromic number. Written other ways, in Roman numerals it is XXII and in binary, 10110.
Interestingness
Historical context — 22 AD
Calendar year
AD 22 (XXII) was a common year starting on Thursday of the Julian calendar.
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Historical context — 22 BC
Calendar year
Year 22 BC was either a common year starting on Sunday, Monday or Tuesday or a leap year starting on Sunday or Saturday of the Julian calendar and a common year starting on Saturday of the Proleptic Julian calendar.
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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
-
Saturday
January 1, 22
- Ended on
-
Saturday
December 31, 22
- Friday the 13ths
-
1
One Friday the 13th this year.
- Decade
-
20s
20–29
- Century
-
1st century
1–100
- Millennium
-
1st millennium
1–1000
- Years ago
-
2,004
2004 years before 2026.
In other calendars
- Hebrew
-
3782 / 3783 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Water zodiac:Horse
Sexagenary cycle position 19 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
565 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
14 / 15 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
-56 / -57 Saka
Indian national calendar; year starts in March.
Properties
Primality
Prime factorization: 2 × 11
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√22 = [4; (1, 2, 4, 2, 1, 8)]
Period length 6 — the block in parentheses repeats forever.
Representations
- In words
- twenty-two
- Ordinal
- 22nd
- Roman numeral
- XXII
- Binary
- 10110
- Octal
- 26
- Hexadecimal
- 0x16
- Base64
- Fg==
- One's complement
- 233 (8-bit)
- Scientific notation
- 2.2 × 10¹
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒌋𒌋𒁹𒁹
- Egyptian hieroglyphic
- 𓎆𓎆𓏺𓏺
- Greek (Milesian)
- κβʹ
- Mayan (base 20)
- 𝋡·𝋢
- Chinese
- 二十二
- Chinese (financial)
- 貳拾貳
Digit at this position in famous constants
- π — Pi (π)
- Digit 22 = 2
- e — Euler's number (e)
- Digit 22 = 0
- φ — Golden ratio (φ)
- Digit 22 = 4
- √2 — Pythagoras's (√2)
- Digit 22 = 1
- ln 2 — Natural log of 2
- Digit 22 = 7
- γ — Euler-Mascheroni (γ)
- Digit 22 = 6
Also seen as
Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 22, here are decompositions:
- 3 + 19 = 22
- 5 + 17 = 22
- 11 + 11 = 22
As an ASCII codepoint, 22 is control character (0x16). ASCII control character.
TCP/UDP port 22 is the well-known port for SSH — Secure Shell — encrypted remote login.
As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.22.
- Address
- 0.0.0.22
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.0.22
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Heard as a frequency, 22 Hz is closest to:
- Concert pitch (A4 = 440 Hz): F0 (21.8 Hz, +14¢)
- Scientific pitch (C4 = 256 Hz): F♯0 (22.6 Hz, -49¢ — about midway to F0)
- Baroque pitch (A4 = 415 Hz): F♯0 (21.8 Hz, +15¢)
As a MIDI note number, 22 is A♯0 (29.1 Hz at concert pitch). (very low — many laptop and phone speakers can't reproduce it)
On the periodic table, atomic number 22 is Titanium (Ti) — period 4.
Related reading
- Egyptian hieroglyphic numerals — Seven hieroglyphs for every power of ten, from a single stroke to a million.