668
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 6
- Divisor Sum
- 1176
- Proper Divisor Sum (Aliquot Sum)
- 508
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 332
- Möbius Function
- 0
- Radical
- 334
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 2
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- no
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- no
- Lucas Number
- no
- Tetrahedral Number
- no
- Pell Number
- no
- Tribonacci Number
- no
- Pronic Number
- no
Recreational
- Happy Number
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 69
- Smith Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- Prime Power
- no
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- no
- Achilles Number
- no
- Perfect Power
- no
- Smooth Number
- no
- Carmichael Number
- no
Classification
- Even
- yes
- Odd
- no
Names
- German
- sechshundertachtundsechzig· ordinal: sechshundertachtundsechzigste
- English
- six hundred sixty-eight· ordinal: six hundred sixty-eighth
- Spanish
- seiscientos sesenta y ocho· ordinal: 668º
- French
- six cent soixante-huit· ordinal: six cent soixante-huitième
- Italian
- seicentosessantotto· ordinal: 668º
- Latin
- sescenti sexaginta octo· ordinal: 668.
- Portuguese
- seiscentos e sessenta e oito· ordinal: 668º
Appears in sequences
- Expansion of Product_{m >= 1} (1 + x^m); number of partitions of n into distinct parts; number of partitions of n into odd parts.at n=36A000009
- a(n) = n! * (1 + 2*Sum_{k=1..n} 1/k).at n=5A000776
- Number of n-bead necklaces with beads of 2 colors and primitive period n, when turning over is allowed.at n=14A001371
- Numbers in which every digit contains at least one loop (version 1).at n=22A001743
- Primes multiplied by 4.at n=38A001749
- Number of partitions of 3n-1 into n nonnegative integers each no more than 6.at n=12A001978
- Expansion of a modular function for Gamma_0(21).at n=13A002511
- RATS: Reverse Add Then Sort the digits applied to previous term, starting with 1.at n=7A004000
- a(n) = round(n*phi^7), where phi is the golden ratio, A001622.at n=23A004942
- a(n) = ceiling(n*phi^7), where phi is the golden ratio, A001622.at n=23A004962
- Numbers whose ternary expansion contains no 1's.at n=53A005823
- Generalized Fibonacci numbers A_{n,4}.at n=25A006209
- a(n) = Sum_{k=1..n-1} (k OR n-k).at n=26A006583
- Coordination sequence T1 for Zeolite Code AFO.at n=17A008015
- Coordination sequence T2 for Zeolite Code BIK.at n=16A008048
- Coordination sequence T2 for Zeolite Code DOH.at n=16A008079
- Coordination sequence T1 for Zeolite Code MFS.at n=16A008173
- 3x+1 sequence starting at 97.at n=49A008873
- 3x+1 sequence starting at 63.at n=38A008874
- 3x+1 sequence starting at 95.at n=36A008875