28 (twenty-eight) is the natural number following 27 and preceding 29.
It is a composite number, its proper divisors being 1, 2, 4, 7, and 14.
Twenty-eight is the second perfect number. As a perfect number, it is related to the Mersenne prime 7, since 22(23 - 1) = 28. The next perfect number is 496, the previous being 6.
Twenty-eight is the third Granville number. The next Granville number is 96, the previous being 24.
Twenty-eight is the sum of the totient function for the first nine integers.
Twenty-eight is not the aliquot sum of any number other than itself and is therefore not a component in an aliquot sequence.
Since the greatest prime factor of 282 + 1 = 785 is 157, which is more than 28 twice, 28 is a Størmer number.
Twenty-eight is a harmonic divisor number, a happy number, a triangular number, a hexagonal number, and a centered nonagonal number.
It appears in the Padovan sequence, preceded by the terms 12, 16, 21 (it is the sum of the first two of these).
It is also a Keith number, because it recurs in a Fibonacci-like sequence started from its base 10 digits: 2, 8, 10, 18, 28...
A number is a mathematical object used to count and measure. In mathematics, the definition of number has been extended over the years to include such numbers as zero, negative numbers, rational numbers, irrational numbers, and complex numbers.
Mathematical operations are certain procedures that take one or more numbers as input and produce a number as output. Unary operations take a single input number and produce a single output number. For example, the successor operation adds one to an integer, thus the successor of 4 is 5. Binary operations take two input numbers and produce a single output number. Examples of binary operations include addition, subtraction, multiplication, division, and exponentiation. The study of numerical operations is called arithmetic.
A notational symbol that represents a number is called a numeral. In addition to their use in counting and measuring, numerals are often used for labels (telephone numbers), for ordering (serial numbers), and for codes (e.g., ISBNs).
Lucky Number | 28 พ.ค. 58 |เลโอ,ชาช่า Full HD
Produkt 28 - My number one (Official, HD + Lyrics)
Frédéric Chopin - Prelude in E-Minor (op.28 no. 4)
Office 2010 Class #28: Excel Number Formatting: Formatting As Façade
Rumpke Mountain Boys 2014-07-20 Number 28
back numberのオールナイトニッポン【2015年4月28日】
back numberのオールナイトニッポン 2015年4月28日 【ゲスト:ストレイテナー ホリエアツシ】
2015 04 28 back numberのオールナイトニッポン ゲスト・STRAIGHTENER ホリエアツシ
Sesame Street - Number Creatures #28
REACH - Playthrough Part 28 - Number One Contender
Raindrop - Prelude Opus 28 Number 15
Cristiano Ronaldo ~ Season 02-03 ~ The Number 28
Frédéric CHOPIN: Op. 28, No. 20 (Prelude)
The Presidents: Number 28: Woodrow Wilson- Part 1
Lucky Number | 28 พ.ค. 58 |เลโอ,ชาช่า Full HD
Produkt 28 - My number one (Official, HD + Lyrics)
Frédéric Chopin - Prelude in E-Minor (op.28 no. 4)
Office 2010 Class #28: Excel Number Formatting: Formatting As Façade
Rumpke Mountain Boys 2014-07-20 Number 28
back numberのオールナイトニッポン【2015年4月28日】
back numberのオールナイトニッポン 2015年4月28日 【ゲスト:ストレイテナー ホリエアツシ】
2015 04 28 back numberのオールナイトニッポン ゲスト・STRAIGHTENER ホリエアツシ
Sesame Street - Number Creatures #28
REACH - Playthrough Part 28 - Number One Contender
Raindrop - Prelude Opus 28 Number 15
Cristiano Ronaldo ~ Season 02-03 ~ The Number 28
Frédéric CHOPIN: Op. 28, No. 20 (Prelude)
The Presidents: Number 28: Woodrow Wilson- Part 1
How Popular are You? - Number Hub (Ep 28) - Head Squeeze
LET'S PLAY: GTA 5 - Part 28 (Pointless Episode Number 2)
Le port de Number ! | Episode 28 - Serveur Redwood | Minecraft
Mysterious Ways - 1x22 - John Doe Number 28 part 3
Smash Book Session Number 28 | NO VO | MyGreenCow
Columbus April 28, 2015 Baby number 3
back numberのオールナイトニッポン 2014年10月28日 バクナンのANN ラジオニッポン放送
Universal Newsreel Volume 28, Number 704, 08/29/1955
To Be Number One Variety 28มี.ค.58
back number ダイノジのスクールナイン 2014年01月28日
【2014.10.28火】back numberのオールナイトニッポン
2014 10 28 back number 栗原寿のオールナイトニッポン
To Be Number One Variety 28ก.พ.58
バクナンのANN 2014年10月28日 back numberのオールナイトニッポン バックナンバーANN ラジオ
ZDF Kultur: Number One: Bruno Mars interview 10/28/2013
Mindcrack Number 28 - "Furnace Shutter" (Z424)
Acesso MTV "AO VIVO" - com Fake Number - 28/10/2011
Jersey Number 10 - Episode 28 - Full Episode
The MSS - Number 57 - 28 July 2013 - with Aronra, HogTieChamp and thunderf00t
X-Wing Miniatures Battle Report - Number 9 - 28-08-2014
Video 14. Quran 72:28, "GOD has counted the number of all things."
AT&T; Conversation Regarding Theft of Phone Number
Hotline Miami 2: Wrong Number OST (WIP) UPDATED V2
Adapting the Atom to Florida Progress - Production number 28 - 1962
back numberのオールナイトニッポン【2014年10月28日】
Matthew Charles - "I've Got Your Number" @ The Civic Lab, Chicago, IL 2/28/2015
Maths By Amiya: Remainder by Two Divisors of a common Number
Seagame 28 Sôi động cùng ca khúc Việt Nam number 1 cổ vũ tuyển U23 thi đấu Cáp Anh Tài
Pixies - Number 13 Baby at Kings Theater, Brooklyn 5/28/15
Basenezmen Live Thessaloniki Finale 28/5/2015
(1-800-824-4013) Karpersky Antivirus Customer Helpline Toll Free Number | Kaspersky Customer Support
ICLOUD Customer Support Phone Number@1-855-776-6916
Let's Learn to Count - Number 6 | From Baby Teacher
Whirlpool Part Number 8531269: PANEL-CNTL
I lost Vincent's Number: Let's Play Final Fantasy VII Steam HD Mod [28]
The Evil Within: Valve And The Number 3 - Game Away - Part 28
28 Shopping Count Input String to Number
LOCK ON THE HUSTLE(Waackin-GO number) / HEAT UP vol.28
En Dolphin☆彡(YU-KO number) / HEAT UP vol.28
sparkling girl(KYONKO number) / HEAT UP vol.28
サンダーボルト!(HIRO number) / HEAT UP vol.28
R.I.A(ゆかちん number) / HEAT UP vol.28
Hotline Miami 2: Wrong Number #28 - Knife!
28 Radio Down Under - Episode 7 - June 2010 - Blood & Honour Australia