Number

72

72 is a composite number, even, a calendar year.

Abundant Number Achilles Number Evil Number Harshad / Niven Pernicious Number Powerful Number Practical Number Pronic / Oblong Recamán's Sequence Semiperfect Number Year

Historical context — 72 AD

Calendar year

AD 72 (LXXII) was a leap year starting on Wednesday of the Julian calendar.

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

Historical context — 72 BC

Calendar year

Year 72 BC was a year of the pre-Julian Roman calendar.

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

Year facts

Year type: Leap year
Divisible by 4 and not by 100; February has 29 days.
Days in year: 366
ISO weeks: 52
Started on: Friday
January 1, 72
Ended on: Saturday
December 31, 72
Friday the 13ths: 1
One Friday the 13th this year.
Decade: 70s
70–79
Century: 1st century
1–100
Millennium: 1st millennium
1–1000
Years ago: 1,954
1954 years before 2026.

In other calendars

Hebrew: 3832 / 3833 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Water zodiac:Monkey
Sexagenary cycle position 9 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 615 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 64 / 65 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): -6 / -7 Saka
Indian national calendar; year starts in March.

Cultural significance

Kabbalistic sacred

The 72 names of God in Kabbalah.

Derived from a permutation of three verses in Exodus 14.

Sourced from Wikipedia (Numerology, Chinese numerology, Gematria, and per-culture articles).

Properties

Parity: Even
Digit count: 2
Digit sum: 9
Digit product: 14
Digital root: 9
Palindrome: No
Bit width: 7 bits
Reversed: 27
Recamán's sequence: a(83) = 72
Square (n²): 5,184
Cube (n³): 373,248
Divisor count: 12
σ(n) — sum of divisors: 195
φ(n) — Euler's totient: 24
Sum of prime factors: 12

Primality

Prime factorization: 2 ³ × 3 ²

Nearest primes: 71 (−1) · 73 (+1)

Divisors & multiples

All divisors (12)

1 · 2 · 3 · 4 · 6 · 8 · 9 · 12 · 18 · 24 · 36 (half) · 72

Aliquot sum (sum of proper divisors): 123

Factor pairs (a × b = 72)

1 × 72

2 × 36

3 × 24

4 × 18

6 × 12

8 × 9

First multiples

72 · 144 (double) · 216 · 288 · 360 · 432 · 504 · 576 · 648 · 720

Sums & aliquot sequence

As a sum of two squares: 6² + 6²

As consecutive integers: 23 + 24 + 25 4 + 5 + … + 12

Aliquot sequence: 72 → 123 → 45 → 33 → 15 → 9 → 4 → 3 → 1 → 0 — terminates at zero

Representations

In words: seventy-two
Ordinal: 72nd
Roman numeral: LXXII
Binary: 1001000
Octal: 110
Hexadecimal: 0x48
Base64: SA==
One's complement: 183 (8-bit)

In other bases

ternary (3) 2200

quaternary (4) 1020

quinary (5) 242

senary (6) 200

septenary (7) 132

nonary (9) 80

undecimal (11) 66

duodecimal (12) 60

tridecimal (13) 57

tetradecimal (14) 52

pentadecimal (15) 4c

Historical numeral systems

Babylonian (base 60): 𒁹 𒌋𒁹𒁹
Egyptian hieroglyphic: 𓎆𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺
Greek (Milesian): οβʹ
Mayan (base 20): 𝋣·𝋬
Chinese: 七十二
Chinese (financial): 柒拾貳

In other modern scripts

Eastern Arabic ٧٢ Devanagari ७२ Bengali ৭২ Tamil ௭௨ Thai ๗๒ Tibetan ༧༢ Khmer ៧២ Lao ໗໒ Burmese ၇၂

Digit at this position in famous constants

π — Pi (π): Digit 72 = 0
e — Euler's number (e): Digit 72 = 3
φ — Golden ratio (φ): Digit 72 = 6
√2 — Pythagoras's (√2): Digit 72 = 7
ln 2 — Natural log of 2: Digit 72 = 2
γ — Euler-Mascheroni (γ): Digit 72 = 2

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 72, here are decompositions:

5 + 67 = 72
11 + 61 = 72
13 + 59 = 72
19 + 53 = 72
29 + 43 = 72
31 + 41 = 72

ASCII character

As an ASCII codepoint, 72 is H. Printable ASCII character H.

Hex color

#000048

RGB(0, 0, 72)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.72.

Address: 0.0.0.72
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.72

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

US numbered highway

Matches numbered highway designation:

I-72 — Hannibal, MO to Champaign, IL.

Interstate 72 on Wikipedia ↗