2175
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 3720
- Proper Divisor Sum (Aliquot Sum)
- 1545
- 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
- 1120
- Möbius Function
- 0
- Radical
- 435
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 3
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
- yes
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 76
- Smith Number
- no
- Vampire 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
- no
- Odd
- yes
Appears in sequences
- Number of permutations of length n by rises.at n=5A001277
- Expansion of 1/((1-x)*(1-x-2*x^3)).at n=14A003479
- Coordination sequence T1 for Zeolite Code EAB.at n=34A008082
- Irregular triangle read by rows: T(n,k) (n>=1, 0 <= k <= floor(n/2)) = number of permutations of 1..n with exactly floor(n/2) - k runs of consecutive pairs up.at n=17A010029
- Waring's problem: least positive integer requiring maximum number of terms when expressed as a sum of positive n-th powers.at n=6A018886
- a(n) = n*(7*n - 1)/2.at n=25A022264
- a(n) is least k such that k and 5k are anagrams in base n (written in base 10).at n=24A023097
- a(n) = (d(n)-r(n))/2, where d = A026066 and r is the periodic sequence with fundamental period (1,0,0,0).at n=18A026067
- 5 times triangular numbers: a(n) = 5*n*(n+1)/2.at n=29A028895
- Number of partitions of n^2 into distinct squares.at n=34A030273
- Positions of record values in A030767.at n=48A030772
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 15.at n=17A031513
- Numbers whose set of base-12 digits is {1,3}.at n=19A032919
- Number of ternary rooted trees with n nodes and height exactly 9.at n=14A036424
- Numerators of continued fraction convergents to sqrt(127).at n=5A041230
- Denominators of continued fraction convergents to sqrt(981).at n=11A042899
- Numbers congruent to 2,3,6,11 mod 12 missing from A042944 (conjectured to be finite).at n=14A042945
- The sequence e when b=[ 1,0,1,1,1,... ].at n=28A042953
- Numbers n such that string 7,7 occurs in the base 8 representation of n but not of n-1.at n=33A044250
- Numbers k such that the string 7,6 occurs in the base 9 representation of k but not of k-1.at n=29A044320