67
67 is a prime, odd, a calendar year.
On paper, 67 is unremarkable — the 19th prime number, sitting quietly between 66 and 68. In 2025 it became something no prime had ever been: a global catchphrase. Written 6-7 and always said aloud as “six-seven” (never “sixty-seven”), it swept through schools and social media as a piece of pure Gen Alpha absurdism, usually punctuated by a two-handed, palms-up gesture that rocks up and down like a set of scales.
The phrase traces to Doot Doot (6 7), a late-2024 track by the Philadelphia rapper Skrilla, and caught fire on TikTok in the summer of 2025 — amplified by basketball edits and a viral clip of a young fan who became known as “the 67 kid.” Searches for the term jumped more than sixfold in a matter of months.
Its defining feature is that it means nothing. Skrilla has said he never attached a meaning to it, and that emptiness is the joke: kids deploy “6-7” as a non-sequitur — an answer to no question, a sound for its own sake — to the well-documented exasperation of teachers everywhere. In October 2025, Dictionary.com named “67” its Word of the Year, a rare case of the honour going to a “word” with, by design, no definition at all.
Interestingness
Historical context — 67 AD
Calendar year
AD 67 (LXVII) was a common year starting on Thursday of the Julian calendar.
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Historical context — 67 BC
Calendar year
Year 67 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
-
Saturday
January 1, 67
- Ended on
-
Saturday
December 31, 67
- 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
-
1,959
1959 years before 2026.
In other calendars
- Hebrew
-
3827 / 3828 AM
Rosh Hashanah falls in September/October.
- Chinese
-
Year of the zodiac:Fire zodiac:Rabbit
Sexagenary cycle position 4 of 60. Lunar new year falls in late January / mid-February.
- Buddhist Era
-
610 BE
Counted from the parinirvana of the Buddha (Theravada / Thai / Sri Lankan convention).
- Ethiopian
-
59 / 60 ET
Year boundary at Enkutatash (September 11/12).
- Indian National (Saka)
-
-11 / -12 Saka
Indian national calendar; year starts in March.
Cultural significance
"6-7" (six-seven) — the viral 2025 catchphrase schoolkids blurt out, often with a two-handed up-and-down "weighing" gesture. Dictionary.com named it the 2025 Word of the Year.
Traced to Philadelphia rapper Skrilla's 2024 song "Doot Doot (6 7)" and spread by basketball TikToks (the "67 kid"); the whole joke is that it means nothing at all — and it's never pronounced "sixty-seven".
Sourced from Wikipedia (Numerology, Chinese numerology, Gematria, and per-culture articles).
Properties
Primality
67 is prime. It has exactly two divisors: 1 and itself.
Divisors & multiples
Sums & aliquot sequence
Continued fraction of √n
√67 = [8; (5, 2, 1, 1, 7, 1, 1, 2, 5, 16)]
Period length 10 — the block in parentheses repeats forever.
Representations
- In words
- sixty-seven
- Ordinal
- 67th
- Roman numeral
- LXVII
- Binary
- 1000011
- Octal
- 103
- Hexadecimal
- 0x43
- Base64
- Qw==
- One's complement
- 188 (8-bit)
- Scientific notation
- 6.7 × 10¹
- As a duration
- 67 s = 1 minute, 7 seconds
As an angle
Historical numeral systems
- Babylonian (base 60)
- 𒁹 𒁹𒁹𒁹𒁹𒁹𒁹𒁹
- Egyptian hieroglyphic
- 𓎆𓎆𓎆𓎆𓎆𓎆𓏺𓏺𓏺𓏺𓏺𓏺𓏺
- Greek (Milesian)
- ξζʹ
- Mayan (base 20)
- 𝋣·𝋧
- Chinese
- 六十七
- Chinese (financial)
- 陸拾柒
Digit at this position in famous constants
- π — Pi (π)
- Digit 67 = 7
- e — Euler's number (e)
- Digit 67 = 4
- φ — Golden ratio (φ)
- Digit 67 = 5
- √2 — Pythagoras's (√2)
- Digit 67 = 0
- ln 2 — Natural log of 2
- Digit 67 = 3
- γ — Euler-Mascheroni (γ)
- Digit 67 = 4
Also seen as
As an ASCII codepoint, 67 is C. Printable ASCII character C.
TCP/UDP port 67 is the well-known port for DHCP server — Dynamic Host Configuration Protocol — server.
As an unsigned 32-bit integer, this is the IPv4 address 0.0.0.67.
- Address
- 0.0.0.67
- Class
- reserved
- IPv4-mapped IPv6
- ::ffff:0.0.0.67
Unspecified address (0.0.0.0/8) — "this network" placeholder.
Heard as a frequency, 67 Hz is closest to:
- Concert pitch (A4 = 440 Hz): C2 (65.4 Hz, +42¢)
- Scientific pitch (C4 = 256 Hz): C♯2 (67.8 Hz, -21¢)
- Baroque pitch (A4 = 415 Hz): C♯2 (65.4 Hz, +43¢)
As a MIDI note number, 67 is G4 (392 Hz at concert pitch).
On the periodic table, atomic number 67 is Holmium (Ho) — period 6.
Related reading
- Prime numbers — The building blocks of arithmetic: what primes are, why they matter, and how we find them.
- Egyptian hieroglyphic numerals — Seven hieroglyphs for every power of ten, from a single stroke to a million.