# 25 (number)

 ← 24 25 26 →
Cardinaltwenty-five
Ordinal25th
(twenty-fifth)
Factorization52
Divisors1, 5, 25
Greek numeralΚΕ´
Roman numeralXXV
Binary110012
Ternary2213
Quaternary1214
Quinary1005
Senary416
Octal318
Duodecimal2112
Vigesimal1520
Base 36P36

25 (twenty-five) is the natural number following 24 and preceding 26.

## In mathematics

25 is a square

It is a square number, being 52 = 5 × 5. It is one of two two-digit numbers whose square and higher powers of the number also ends in the same last two digits, e.g. 252 = 625, the other is 76. It is the smallest square that is also a sum of two (non-zero) squares: 25 = 32 + 42. Hence it often appears in illustrations of the Pythagorean theorem.

25 is the sum of the single-digit odd natural numbers 1, 3, 5, 7 and 9, the first five odd natural numbers.

25 percent (%) is equal to 1/4.

It is the smallest base 10 Friedman number as it can be expressed by its own digits: 52.[4]

It is also a Cullen number.[5] 25 is the smallest pseudoprime satisfying the congruence 7n = 7 mod n.

25 is the smallest aspiring number — a composite non-sociable number whose aliquot sequence does not terminate.[6]

According to the Shapiro inequality, 25 is the least odd integer n such that there exist x1, x2, …, xn such that

${\displaystyle \sum _{i=1}^{n}{\frac {x_{i}}{x_{i+1}+x_{i+2}}}<{\frac {n}{2}}}$

where xn + 1 = x1, xn + 2 = x2.

Within base 10 one can readily test for divisibility by 25 by seeing if the last two digits of the number match 00, 25, 50 or 75.

Other Languages
العربية: 25 (عدد)
azərbaycanca: 25 (ədəd)
تۆرکجه: ۲۵ (سایی)
Bân-lâm-gú: 25
български: 25 (число)
བོད་ཡིག: ༢༥ (གྲངས་ཀ།)
català: Vint-i-cinc
Чӑвашла: 25 (хисеп)
čeština: 25 (číslo)
dansk: 25 (tal)
Ελληνικά: 25 (αριθμός)
emiliàn e rumagnòl: 25 (nùmer)
español: Veinticinco
Esperanto: 25 (nombro)
euskara: Hogeita bost
فارسی: ۲۵ (عدد)
føroyskt: 25 (tal)
français: 25 (nombre)
Gaeilge: 25 (uimhir)

한국어: 25
հայերեն: 25 (թիվ)
Bahasa Indonesia: 25 (angka)
interlingua: 25 (numero)
italiano: 25 (numero)
עברית: 25 (מספר)
ქართული: 25 (რიცხვი)
Kiswahili: Ishirini na tano
Kreyòl ayisyen: 25 (nonm)
latviešu: 25 (skaitlis)
lietuvių: 25 (skaičius)
magyar: 25 (szám)
македонски: 25 (број)
Bahasa Melayu: 25 (nombor)
Mìng-dĕ̤ng-ngṳ̄: 25
Nederlands: 25 (getal)

Napulitano: Vinticìnche
norsk: 25 (tall)
norsk nynorsk: Talet 25
oʻzbekcha/ўзбекча: 25 (son)
پنجابی: 25
پښتو: ۲۵ (عدد)
polski: 25 (liczba)
português: Vinte e cinco
русский: 25 (число)
Sesotho sa Leboa: 25 (nomoro)
Simple English: 25 (number)
slovenščina: 25 (število)
Soomaaliga: 25 (tiro)
کوردی: ٢٥ (ژمارە)
Sranantongo: Numro 25
српски / srpski: 25 (број)
suomi: 25 (luku)
svenska: 25 (tal)
татарча/tatarça: 25 (сан)
తెలుగు: 25 (సంఖ్య)
ไทย: 25
Türkçe: 25 (sayı)
тыва дыл: 25
українська: 25 (число)
اردو: 25 (عدد)
Vahcuengh: 25
vepsän kel’: 25 (lugu)
Tiếng Việt: 25 (số)
West-Vlams: 25 (getal)
Winaray: 25 (ihap)
ייִדיש: 25 (נומער)