Number

165

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

165 (one hundred sixty-five) is an odd 3-digit number. It is a composite number with 8 divisors, and factors as 3 × 5 × 11. Written other ways, in Roman numerals it is CLXV and in binary, 10100101.

Arithmetic Number Binary Palindrome Cube-Free Deficient Number Evil Number Gapful Number Recamán's Sequence Self Number Sphenic Number Squarefree Tetrahedral Year

Interestingness

★ ★ ★ ★ ★

9 notable facts · grade A

153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177

less more

Historical context — 165 AD

Calendar year

Year 165 (CLXV) was a common year starting on Monday of the Julian calendar.

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

Historical context — 165 BC

Calendar year

Year 165 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: Tuesday
January 1, 165
Ended on: Tuesday
December 31, 165
Friday the 13ths: 2
2 Friday the 13ths this year.
Decade: 160s
160–169
Century: 2nd century
101–200
Millennium: 1st millennium
1–1000
Years ago: 1,861
1861 years before 2026.

In other calendars

Hebrew: 3925 / 3926 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: 708 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 157 / 158 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 87 / 86 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 12
Digit product: 30
Digital root: 3
Palindrome: No
Bit width: 8 bits
Reversed: 561
Recamán's sequence: a(337) = 165
Square (n²): 27,225
Cube (n³): 4,492,125
Divisor count: 8
σ(n) — sum of divisors: 288
φ(n) — Euler's totient: 80
Sum of prime factors: 19

Primality

Prime factorization: 3 × 5 × 11

Nearest primes: 163 (−2) · 167 (+2)

Divisors & multiples

All divisors (8)

1 · 3 · 5 · 11 · 15 · 33 · 55 · 165

Aliquot sum (sum of proper divisors): 123

Factor pairs (a × b = 165)

1 × 165

3 × 55

5 × 33

11 × 15

First multiples

165 · 330 (double) · 495 · 660 · 825 · 990 · 1,155 · 1,320 · 1,485 · 1,650

Sums & aliquot sequence

As consecutive integers: 82 + 83 54 + 55 + 56 31 + 32 + 33 + 34 + 35 25 + 26 + 27 + 28 + 29 + 30

Aliquot sequence: 165 → 123 → 45 → 33 → 15 → 9 → 4 → 3 → 1 → 0 — terminates at zero

Continued fraction of √n

√165 = [12; (1, 5, 2, 5, 1, 24)]

Period length 6 — the block in parentheses repeats forever.

Representations

In words: one hundred sixty-five
Ordinal: 165th
Roman numeral: CLXV
Binary: 10100101
Octal: 245
Hexadecimal: 0xA5
Base64: pQ==
One's complement: 90 (8-bit)
Scientific notation: 1.65 × 10²
As a duration: 165 s = 2 minutes, 45 seconds

In other bases

ternary (3) 20010

quaternary (4) 2211

quinary (5) 1130

senary (6) 433

septenary (7) 324

nonary (9) 203

undecimal (11) 140

duodecimal (12) 119

tridecimal (13) c9

tetradecimal (14) bb

pentadecimal (15) b0

Palindromic in base 2

As an angle

165°

165° ≈ 2.88 rad

Compass bearing: SSE (south-southeast)

Why does a circle have 360 degrees? →

Historical numeral systems

Babylonian (base 60): 𒁹𒁹 𒌋𒌋𒌋𒌋𒁹𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓍢𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺
Greek (Milesian): ρξεʹ
Mayan (base 20): 𝋨·𝋥
Chinese: 一百六十五
Chinese (financial): 壹佰陸拾伍

In other modern scripts

Eastern Arabic ١٦٥ Devanagari १६५ Bengali ১৬৫ Tamil ௧௬௫ Thai ๑๖๕ Tibetan ༡༦༥ Khmer ១៦៥ Lao ໑໖໕ Burmese ၁၆၅

Digit at this position in famous constants

π — Pi (π): Digit 165 = 0
e — Euler's number (e): Digit 165 = 2
φ — Golden ratio (φ): Digit 165 = 8
√2 — Pythagoras's (√2): Digit 165 = 6
ln 2 — Natural log of 2: Digit 165 = 7
γ — Euler-Mascheroni (γ): Digit 165 = 3

Also seen as

Unicode codepoint

Yen Sign

U+00A5

Currency symbol (Sc)

UTF-8 encoding: C2 A5 (2 bytes).

Lookup U+00A5 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#0000A5

RGB(0, 0, 165)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.165.

Address: 0.0.0.165
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.165

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

Musical pitch

Heard as a frequency, 165 Hz is closest to:

Concert pitch (A4 = 440 Hz): E3 (164.8 Hz, +2¢)
Scientific pitch (C4 = 256 Hz): E3 (161.3 Hz, +40¢)
Baroque pitch (A4 = 415 Hz): F3 (164.7 Hz, +3¢)