669
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 896
- Proper Divisor Sum (Aliquot Sum)
- 227
- 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
- 444
- Möbius Function
- 1
- Radical
- 669
- Omega Function (Ω)
- 2
- 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
- yes
- Squarefree Number
- yes
- 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
- no
- Odd
- yes
Names
- German
- sechshundertneunundsechzig· ordinal: sechshundertneunundsechzigste
- English
- six hundred sixty-nine· ordinal: six hundred sixty-ninth
- Spanish
- seiscientos sesenta y nueve· ordinal: 669º
- French
- six cent soixante-neuf· ordinal: six cent soixante-neufième
- Italian
- seicentosessantanove· ordinal: 669º
- Latin
- sescenti sexaginta novem· ordinal: 669.
- Portuguese
- seiscentos e sessenta e nove· ordinal: 669º
Appears in sequences
- Number of asymmetrical dissections of n-gon.at n=5A000131
- Numbers in which every digit contains at least one loop (version 1).at n=23A001743
- a(n) = 3 * prime(n).at n=47A001748
- Number of equivalence classes of binary sequences of primitive period n.at n=15A002730
- Expansion of g.f.: (1+x^3)*(1+x^4)/((1-x)*(1-x^2)^2*(1-x^4)).at n=24A004657
- Number of elements in Z[ i ] whose 'smallest algorithm' is <= n.at n=6A006457
- Coordination sequence T4 for Zeolite Code LTN.at n=18A008143
- Coordination sequence T4 for Zeolite Code RTH.at n=18A009896
- Coordination sequence T1 for Zeolite Code RUT.at n=17A009897
- Coordination sequence T6 for Zeolite Code VNI.at n=16A009912
- Coefficients in expansion of Pi as Sum_{n>=1} a(n)/(n*n!*(n+1)!), as found by greedy algorithm.at n=29A011191
- Three-fold convolution of primes with themselves.at n=4A014343
- Sum of all the digits of n in every base from 2 to n-1.at n=54A014837
- Expansion of (1 - x + x^4) / (1 - x)^3.at n=38A016028
- Blum integers: numbers of the form p * q where p and q are distinct primes congruent to 3 (mod 4).at n=43A016105
- Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite BEA = Beta Na7[Al7Si57O128] starting with a T2 atom.at n=9A019068
- From George Gilbert's marks problem: jumping 6 marks at a time (final positions).at n=6A019996
- Numbers k such that the continued fraction for sqrt(k) has period 38.at n=1A020377
- Place where n-th 1 occurs in A007337.at n=27A022777
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (natural numbers >= 3), t = (Lucas numbers).at n=7A024877