Number

145

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

Arithmetic Number Ascending Digits Deficient Number Odious Number Pentagonal Pernicious Number Recamán's Sequence Semiprime Squarefree Year

Historical context — 145 AD

Calendar year

Year 145 (CXLV) was a common year starting on Thursday of the Julian calendar.

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Historical context — 145 BC

Calendar year

Year 145 BC was a year of the pre-Julian Roman 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: Friday
January 1, 145
Ended on: Friday
December 31, 145
Friday the 13ths: 1
One Friday the 13th this year.
Decade: 140s
140–149
Century: 2nd century
101–200
Millennium: 1st millennium
1–1000
Years ago: 1,881
1881 years before 2026.

In other calendars

Hebrew: 3905 / 3906 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: 688 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 137 / 138 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): 67 / 66 Saka
Indian national calendar; year starts in March.

Properties

Parity: Odd
Digit count: 3
Digit sum: 10
Digit product: 20
Digital root: 1
Palindrome: No
Bit width: 8 bits
Reversed: 541
Recamán's sequence: a(742) = 145
Square (n²): 21,025
Cube (n³): 3,048,625
Divisor count: 4
σ(n) — sum of divisors: 180
φ(n) — Euler's totient: 112
Sum of prime factors: 34

Primality

Prime factorization: 5 × 29

Nearest primes: 139 (−6) · 149 (+4)

Divisors & multiples

All divisors (4)

1 · 5 · 29 · 145

Aliquot sum (sum of proper divisors): 35

Factor pairs (a × b = 145)

1 × 145

5 × 29

First multiples

145 · 290 (double) · 435 · 580 · 725 · 870 · 1,015 · 1,160 · 1,305 · 1,450

Sums & aliquot sequence

As a sum of two squares: 1² + 12² = 8² + 9²

As consecutive integers: 72 + 73 27 + 28 + 29 + 30 + 31 10 + 11 + … + 19

Aliquot sequence: 145 → 35 → 13 → 1 → 0 — terminates at zero

Representations

In words: one hundred forty-five
Ordinal: 145th
Roman numeral: CXLV
Binary: 10010001
Octal: 221
Hexadecimal: 0x91
Base64: kQ==
One's complement: 110 (8-bit)

In other bases

ternary (3) 12101

quaternary (4) 2101

quinary (5) 1040

senary (6) 401

septenary (7) 265

nonary (9) 171

undecimal (11) 122

duodecimal (12) 101

tridecimal (13) b2

tetradecimal (14) a5

pentadecimal (15) 9a

Historical numeral systems

Babylonian (base 60): 𒁹𒁹 𒌋𒌋𒁹𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓍢𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺
Greek (Milesian): ρμεʹ
Mayan (base 20): 𝋧·𝋥
Chinese: 一百四十五
Chinese (financial): 壹佰肆拾伍

In other modern scripts

Eastern Arabic ١٤٥ Devanagari १४५ Bengali ১৪৫ Tamil ௧௪௫ Thai ๑๔๕ Tibetan ༡༤༥ Khmer ១៤៥ Lao ໑໔໕ Burmese ၁၄၅

Digit at this position in famous constants

π — Pi (π): Digit 145 = 9
e — Euler's number (e): Digit 145 = 4
φ — Golden ratio (φ): Digit 145 = 0
√2 — Pythagoras's (√2): Digit 145 = 1
ln 2 — Natural log of 2: Digit 145 = 0
γ — Euler-Mascheroni (γ): Digit 145 = 3

Also seen as

Unicode codepoint

Private Use One

U+0091

Control character (Cc)

UTF-8 encoding: C2 91 (2 bytes).

Lookup U+0091 on Compart ↗ Lookup on FileFormat.Info ↗

Hex color

#000091

RGB(0, 0, 145)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.145.

Address: 0.0.0.145
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.145

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