Number

25

25 is a composite number, odd, a calendar year.

Automorphic Number Cullen Number Deficient Number Odious Number Perfect Square Pernicious Number Powerful Number Recamán's Sequence Semiprime Year

Historical context — 25 AD

Calendar year

AD 25 (XXV) was a common year starting on Monday of the Julian calendar.

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Historical context — 25 BC

Calendar year

Year 25 BC was either a common year starting on Wednesday, Thursday or Friday or a leap year starting on Wednesday or Thursday of the Julian calendar and a leap year starting on Tuesday 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: Wednesday
January 1, 25
Ended on: Wednesday
December 31, 25
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: 2,001
2001 years before 2026.

In other calendars

Hebrew: 3785 / 3786 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Wood zodiac:Rooster
Sexagenary cycle position 22 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 568 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 17 / 18 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): -53 / -54 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 2
Digit sum: 7
Digit product: 10
Digital root: 7
Palindrome: No
Bit width: 5 bits
Reversed: 52
Recamán's sequence: a(17) = 25
Square (n²): 625
Cube (n³): 15,625
Square root (√n): 5
Divisor count: 3
σ(n) — sum of divisors: 31
φ(n) — Euler's totient: 20
Sum of prime factors: 10

Primality

Prime factorization: 5 ²

Nearest primes: 23 (−2) · 29 (+4)

Divisors & multiples

All divisors (3)

1 · 5 · 25

Aliquot sum (sum of proper divisors): 6

Factor pairs (a × b = 25)

1 × 25

5 × 5

First multiples

25 · 50 (double) · 75 · 100 · 125 · 150 · 175 · 200 · 225 · 250

Sums & aliquot sequence

As a sum of two squares: 0² + 5² = 3² + 4²

As consecutive integers: 12 + 13 3 + 4 + 5 + 6 + 7

Aliquot sequence: 25 → 6 → 6 — reaches a perfect number

Representations

In words: twenty-five
Ordinal: 25th
Roman numeral: XXV
Binary: 11001
Octal: 31
Hexadecimal: 0x19
Base64: GQ==
One's complement: 230 (8-bit)

In other bases

ternary (3) 221

quaternary (4) 121

quinary (5) 100

senary (6) 41

septenary (7) 34

nonary (9) 27

undecimal (11) 23

duodecimal (12) 21

tridecimal (13) 1c

tetradecimal (14) 1b

pentadecimal (15) 1a

Historical numeral systems

Babylonian (base 60): 𒌋𒌋𒁹𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓎆𓎆𓏺𓏺𓏺𓏺𓏺
Greek (Milesian): κεʹ
Mayan (base 20): 𝋡·𝋥
Chinese: 二十五
Chinese (financial): 貳拾伍

In other modern scripts

Eastern Arabic ٢٥ Devanagari २५ Bengali ২৫ Tamil ௨௫ Thai ๒๕ Tibetan ༢༥ Khmer ២៥ Lao ໒໕ Burmese ၂၅

Digit at this position in famous constants

π — Pi (π): Digit 25 = 3
e — Euler's number (e): Digit 25 = 7
φ — Golden ratio (φ): Digit 25 = 6
√2 — Pythagoras's (√2): Digit 25 = 8
ln 2 — Natural log of 2: Digit 25 = 2
γ — Euler-Mascheroni (γ): Digit 25 = 2

Also seen as

ASCII character

As an ASCII codepoint, 25 is control character (0x19). ASCII control character.

Network port

TCP/UDP port 25 is the well-known port for SMTP — Simple Mail Transfer Protocol.

Hex color

#000019

RGB(0, 0, 25)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.25.

Address: 0.0.0.25
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.25

Unspecified address (0.0.0.0/8) — "this network" placeholder.

US numbered highway

Matches numbered highway designation:

I-25 — Las Cruces, NM to Buffalo, WY.

Interstate 25 on Wikipedia ↗