67 (number)

← 66 67 68 →
← 60 61 62 63 64 65 66 67 68 69 → List of numbers Integers ← 0 10 20 30 40 50 60 70 80 90 →
Cardinal	sixty-seven
Ordinal	67th (sixty-seventh)
Factorization	prime
Prime	19th
Divisors	1, 67
Greek numeral	ΞΖ´
Roman numeral	LXVII, lxvii
Binary	10000112
Ternary	21113
Senary	1516
Octal	1038
Duodecimal	5712
Hexadecimal	4316

67 (six-seven) is the natural number following 66 and preceding 68. It is an odd and prime number.

In mathematics

67 is:

• the 19th prime number (the next is 71).
• a Chen prime. ^[1]
• an irregular prime. ^[2]
• a lucky prime. ^[3]
• the sum of five consecutive primes (7 + 11 + 13 + 17 + 19).
• a Heegner number. ^[4]
• a Pillai prime since 18! + 1 is divisible by 67, but 67 is not one more than a multiple of 18. ^[5]
• palindromic in quinary (232₅) and senary (151₆).
• a super-prime. (19 is prime)
• an isolated prime. (65 and 69 are not prime)
• a sexy prime with 61 and 73

References

1. "Sloane's A109611: Chen primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2021-01-08.
2. "Sloane's A000928 : Irregular primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-29.
3. "Sloane's A031157 : Numbers that are both lucky and prime". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-29.
4. "Sloane's A003173 : Heegner numbers". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-29.
5. "Sloane's A063980 : Pillai primes". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-29.