Number

64

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

Cake Number Centered Triangular Deficient Number Odious Number Perfect Cube Perfect Square Power of Two Powerful Number Practical Number Recamán's Sequence Self Number Superperfect Number Year

Notable events — 64 AD

Jul 19 The Great Fire of Rome burns for six days; Nero blames Christians.

Events compiled from Wikipedia ↗ · Licensed CC BY-SA 4.0

Historical context — 64 BC

Calendar year

Year 64 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: Tuesday
January 1, 64
Ended on: Wednesday
December 31, 64
Friday the 13ths: 1
One Friday the 13th this year.
Decade: 60s
60–69
Century: 1st century
1–100
Millennium: 1st millennium
1–1000
Years ago: 1,962
1962 years before 2026.

In other calendars

Hebrew: 3824 / 3825 AM
Rosh Hashanah falls in September/October.
Chinese: Year of the zodiac:Wood zodiac:Rat
Sexagenary cycle position 1 of 60. Lunar new year falls in late January / mid-February.
Buddhist Era: 607 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
Ethiopian: 56 / 57 ET
Year boundary at Enkutatash (September 11/12).
Indian National (Saka): -14 / -15 Saka
Indian national calendar; year starts in March.

Properties

Parity: Even
Digit count: 2
Digit sum: 10
Digit product: 24
Digital root: 1
Palindrome: No
Bit width: 7 bits
Reversed: 46
Recamán's sequence: a(99) = 64
Square (n²): 4,096
Cube (n³): 262,144
Square root (√n): 8
Cube root (∛n): 4
Divisor count: 7
σ(n) — sum of divisors: 127
φ(n) — Euler's totient: 32
Sum of prime factors: 12

Primality

Prime factorization: 2 ⁶

Nearest primes: 61 (−3) · 67 (+3)

Divisors & multiples

All divisors (7)

1 · 2 · 4 · 8 · 16 · 32 (half) · 64

Aliquot sum (sum of proper divisors): 63

Factor pairs (a × b = 64)

1 × 64

2 × 32

4 × 16

8 × 8

First multiples

64 · 128 (double) · 192 · 256 · 320 · 384 · 448 · 512 · 576 · 640

Sums & aliquot sequence

As a sum of two squares: 0² + 8²

Aliquot sequence: 64 → 63 → 41 → 1 → 0 — terminates at zero

Representations

In words: sixty-four
Ordinal: 64th
Roman numeral: LXIV
Binary: 1000000
Octal: 100
Hexadecimal: 0x40
Base64: QA==
One's complement: 191 (8-bit)
Scientific notation: 6.4 × 10¹

In other bases

ternary (3) 2101

quaternary (4) 1000

quinary (5) 224

senary (6) 144

septenary (7) 121

nonary (9) 71

undecimal (11) 59

duodecimal (12) 54

tridecimal (13) 4c

tetradecimal (14) 48

pentadecimal (15) 44

Palindromic in base 7

Historical numeral systems

Babylonian (base 60): 𒁹 𒁹𒁹𒁹𒁹
Egyptian hieroglyphic: 𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺
Greek (Milesian): ξδʹ
Mayan (base 20): 𝋣·𝋤
Chinese: 六十四
Chinese (financial): 陸拾肆

In other modern scripts

Eastern Arabic ٦٤ Devanagari ६४ Bengali ৬৪ Tamil ௬௪ Thai ๖๔ Tibetan ༦༤ Khmer ៦៤ Lao ໖໔ Burmese ၆၄

Digit at this position in famous constants

π — Pi (π): Digit 64 = 2
e — Euler's number (e): Digit 64 = 7
φ — Golden ratio (φ): Digit 64 = 2
√2 — Pythagoras's (√2): Digit 64 = 7
ln 2 — Natural log of 2: Digit 64 = 9
γ — Euler-Mascheroni (γ): Digit 64 = 4

Also seen as

Goldbach decomposition

Goldbach's conjecture says every even integer greater than 2 is the sum of two primes. For 64, here are decompositions:

3 + 61 = 64
5 + 59 = 64
11 + 53 = 64
17 + 47 = 64
23 + 41 = 64

ASCII character

As an ASCII codepoint, 64 is @. Printable ASCII character @.

Hex color

#000040

RGB(0, 0, 64)

IPv4 address

As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.64.

Address: 0.0.0.64
Class: reserved
IPv4-mapped IPv6: ::ffff:0.0.0.64

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

US numbered highway

Matches numbered highway designation:

I-64 — Wentzville, MO to Chesapeake, VA.

Interstate 64 on Wikipedia ↗

Musical pitch

Heard as a frequency, 64 Hz is closest to:

Concert pitch (A4 = 440 Hz): C2 (-38¢)
Scientific pitch (C4 = 256 Hz): C2 (exact)