Number

105

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

105 (one hundred five) is an odd 3-digit number. It is a composite number with 8 divisors, and factors as 3 × 5 × 7. It is the fourteenth triangular number. Written other ways, in Roman numerals it is CV and in binary, 1101001.

Arithmetic Number Cube-Free Deficient Number Evil Number Gapful Number Recamán's Sequence Sphenic Number Squarefree Triangular Year

Interestingness

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7 notable facts · grade B

93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117

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Historical context — 105 AD

Calendar year

Year 105 (CV) 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 — 105 BC

Calendar year

Year 105 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: 53
Long year: contains 53 ISO weeks.
Started on: Thursday
January 1, 105
Ended on: Thursday
December 31, 105
Friday the 13ths: 3
3 Friday the 13ths this year.
Decade: 100s
100–109
Century: 2nd century
101–200
Millennium: 1st millennium
1–1000
Years ago: 1,921
1921 years before 2026.

In other calendars

Hebrew: 3865 / 3866 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Wood zodiac:Snake
Sexagenary cycle position 42 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 648 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 97 / 98 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 27 / 26 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 6
Digit product: 0
Digital root: 6
Palindrome: No
Bit width: 7 bits
Reversed: 501
Recamán's sequence: a(377) = 105
Square (n²): 11,025
Cube (n³): 1,157,625
Divisor count: 8
σ(n) — sum of divisors: 192
φ(n) — Euler's totient: 48
Sum of prime factors: 15

Primality

Prime factorization: 3 × 5 × 7

Nearest primes: 103 (−2) · 107 (+2)

Divisors & multiples

All divisors (8)

1 · 3 · 5 · 7 · 15 · 21 · 35 · 105

Aliquot sum (sum of proper divisors): 87

Factor pairs (a × b = 105)

1 × 105

3 × 35

5 × 21

7 × 15

First multiples

105 · 210 (double) · 315 · 420 · 525 · 630 · 735 · 840 · 945 · 1,050

Sums & aliquot sequence

As consecutive integers: 52 + 53 34 + 35 + 36 19 + 20 + 21 + 22 + 23 15 + 16 + 17 + 18 + 19 + 20

Aliquot sequence: 105 → 87 → 33 → 15 → 9 → 4 → 3 → 1 → 0 — terminates at zero

Continued fraction of √n

√105 = [10; (4, 20)]

Period length 2 — the block in parentheses repeats forever.

Representations

In words: one hundred five
Ordinal: 105th
Roman numeral: CV
Binary: 1101001
Octal: 151
Hexadecimal: 0x69
Base64: aQ==
One's complement: 150 (8-bit)
Scientific notation: 1.05 × 10²
As a duration: 105 s = 1 minute, 45 seconds

In other bases

ternary (3) 10220

quaternary (4) 1221

quinary (5) 410

senary (6) 253

septenary (7) 210

nonary (9) 126

undecimal (11) 96

duodecimal (12) 89

tridecimal (13) 81

tetradecimal (14) 77

pentadecimal (15) 70

Palindromic in base 4, base 8

As an angle

105°

105° ≈ 1.833 rad

Compass bearing: ESE (east-southeast)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒁹 𒌋𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓍢𓏺𓏺𓏺𓏺𓏺
Greek (Milesian): ρεʹ
Mayan (base 20): 𝋥·𝋥
Chinese: 一百零五
Chinese (financial): 壹佰零伍

In other modern scripts

Eastern Arabic ١٠٥ Devanagari १०५ Bengali ১০৫ Tamil ௧௦௫ Thai ๑๐๕ Tibetan ༡༠༥ Khmer ១០៥ Lao ໑໐໕ Burmese ၁၀၅

Digit at this position in famous constants

π — Pi (π): Digit 105 = 4
e — Euler's number (e): Digit 105 = 6
φ — Golden ratio (φ): Digit 105 = 5
√2 — Pythagoras's (√2): Digit 105 = 1
ln 2 — Natural log of 2: Digit 105 = 0
γ — Euler-Mascheroni (γ): Digit 105 = 3

Also seen as

ASCII character

As an ASCII codepoint, 105 is i. Printable ASCII character i.

Hex color

#000069

RGB(0, 0, 105)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.105.

Address: 0.0.0.105
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.105

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

Musical pitch

Heard as a frequency, 105 Hz is closest to:

Concert pitch (A4 = 440 Hz): G♯2 (103.8 Hz, +19¢)
Scientific pitch (C4 = 256 Hz): A2 (107.6 Hz, -43¢)
Baroque pitch (A4 = 415 Hz): A2 (103.8 Hz, +21¢)

(very low — many laptop and phone speakers can't reproduce it)

As a MIDI note number, 105 is A7 (3520 Hz at concert pitch).

Atomic number

On the periodic table, atomic number 105 is Dubnium (Db) — period 7.

Dubnium on Wikipedia ↗