Number

245

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

245 (two hundred forty-five) is an odd 3-digit number. It is a composite number with 6 divisors, and factors as 5 × 7². Written other ways, in Roman numerals it is CCXLV and in binary, 11110101.

Arithmetic Number Ascending Digits Cube-Free Deficient Number Evil Number Recamán's Sequence Year

Interestingness

★ ★ ☆ ☆ ☆

4 notable facts · grade D

233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257

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Historical context — 245 AD

Calendar year

Year 245 (CCXLV) was a common year starting on Wednesday of the Julian calendar.

Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 Read the full article on Wikipedia →

Historical context — 245 BC

Calendar year

The year 245 BC was a year of the pre-Julian Roman calendar.

Excerpt from Wikipedia (en) ↗ · Licensed CC BY-SA 4.0 Read the full article on Wikipedia →

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, 245
Ended on: Wednesday
December 31, 245
Friday the 13ths: 1
One Friday the 13th this year.
Decade: 240s
240–249
Century: 3rd century
201–300
Millennium: 1st millennium
1–1000
Years ago: 1,781
1781 years before 2026.

In other calendars

Hebrew: 4005 / 4006 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Wood zodiac:Ox
Sexagenary cycle position 2 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 788 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 237 / 238 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 167 / 166 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 11
Digit product: 40
Digital root: 2
Palindrome: No
Bit width: 8 bits
Reversed: 542
Recamán's sequence: a(253) = 245
Square (n²): 60,025
Cube (n³): 14,706,125
Divisor count: 6
σ(n) — sum of divisors: 342
φ(n) — Euler's totient: 168
Sum of prime factors: 19

Primality

Prime factorization: 5 × 7 ²

Nearest primes: 241 (−4) · 251 (+6)

Divisors & multiples

All divisors (6)

1 · 5 · 7 · 35 · 49 · 245

Aliquot sum (sum of proper divisors): 97

Factor pairs (a × b = 245)

1 × 245

5 × 49

7 × 35

First multiples

245 · 490 (double) · 735 · 980 · 1,225 · 1,470 · 1,715 · 1,960 · 2,205 · 2,450

Sums & aliquot sequence

As a sum of two squares: 7² + 14²

As consecutive integers: 122 + 123 47 + 48 + 49 + 50 + 51 32 + 33 + … + 38 20 + 21 + … + 29

Aliquot sequence: 245 → 97 → 1 → 0 — terminates at zero

Continued fraction of √n

√245 = [15; (1, 1, 1, 7, 6, 7, 1, 1, 1, 30)]

Period length 10 — the block in parentheses repeats forever.

Representations

In words: two hundred forty-five
Ordinal: 245th
Roman numeral: CCXLV
Binary: 11110101
Octal: 365
Hexadecimal: 0xF5
Base64: 9Q==
One's complement: 10 (8-bit)
Scientific notation: 2.45 × 10²
As a duration: 245 s = 4 minutes, 5 seconds

In other bases

ternary (3) 100002

quaternary (4) 3311

quinary (5) 1440

senary (6) 1045

septenary (7) 500

nonary (9) 302

undecimal (11) 203

duodecimal (12) 185

tridecimal (13) 15b

tetradecimal (14) 137

pentadecimal (15) 115

As an angle

245°

245° ≈ 4.276 rad

Compass bearing: WSW (west-southwest)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒁹𒁹𒁹𒁹 𒁹𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓍢𓍢𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺
Greek (Milesian): σμεʹ
Mayan (base 20): 𝋬·𝋥
Chinese: 二百四十五
Chinese (financial): 貳佰肆拾伍

In other modern scripts

Eastern Arabic ٢٤٥ Devanagari २४५ Bengali ২৪৫ Tamil ௨௪௫ Thai ๒๔๕ Tibetan ༢༤༥ Khmer ២៤៥ Lao ໒໔໕ Burmese ၂၄၅

Digit at this position in famous constants

π — Pi (π): Digit 245 = 2
e — Euler's number (e): Digit 245 = 4
φ — Golden ratio (φ): Digit 245 = 6
√2 — Pythagoras's (√2): Digit 245 = 8
ln 2 — Natural log of 2: Digit 245 = 7
γ — Euler-Mascheroni (γ): Digit 245 = 5

Also seen as

Unicode codepoint

Latin Small Letter O With Tilde

U+00F5

Lowercase letter (Ll)

UTF-8 encoding: C3 B5 (2 bytes).

Lookup U+00F5 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#0000F5

RGB(0, 0, 245)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.245.

Address: 0.0.0.245
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.245

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

Musical pitch

Heard as a frequency, 245 Hz is closest to:

Concert pitch (A4 = 440 Hz): B3 (246.9 Hz, -14¢)
Scientific pitch (C4 = 256 Hz): B3 (241.6 Hz, +24¢)
Baroque pitch (A4 = 415 Hz): C4 (246.8 Hz, -12¢)