7428
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 17360
- Proper Divisor Sum (Aliquot Sum)
- 9932
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 2472
- Möbius Function
- 0
- Radical
- 3714
- 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
- no
- Narcissistic Number
- no
- Collatz Steps
- 39
- 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
- yes
- Odd
- no
Appears in sequences
- a(n) = number of integer strings s(0),...,s(n) counted by array T in A026386 that have s(n)=4; also a(n) = T(2n,n-2).at n=5A026389
- a(n) = Sum_{k=0..n-2} T(n,k) * T(n,k+2), with T given by A026374.at n=5A026948
- a(n) = Sum_{k=0..n-2} T(n,k) * T(n,k+2), with T given by A026386.at n=5A026953
- 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 56.at n=38A031554
- Numbers whose base-3 representation has exactly 9 runs.at n=8A043589
- Numbers n such that number of runs in the base 3 representation of n is congruent to 1 mod 8.at n=24A043799
- Numbers n such that number of runs in the base 3 representation of n is congruent to 0 mod 9.at n=8A043806
- Numbers k such that number of runs in the base 3 representation of k is congruent to 9 mod 10.at n=8A043824
- Number of labeled planar trees with n nodes such that the root is smaller than all its children.at n=4A071213
- Number of ways to label the vertices of the octahedron (or faces of the cube) with nonnegative integers summing to n, where labelings that differ only by rotation or reflection are considered the same.at n=29A097513
- Numbers k such that 3*10^k + 6*R_k + 1 is prime, where R_k = 11...1 is the repunit (A002275) of length k.at n=10A102975
- Concatenation of first two digits and last two digits of n-th even perfect number.at n=41A138875
- Number of lines through at least 2 points of a 10 X n grid of points.at n=18A160850
- Number of nX5 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 3,4,2,0,1 for x=0,1,2,3,4.at n=6A196860
- Number of nX7 0..4 arrays with each element x equal to the number its horizontal and vertical neighbors equal to 3,4,2,0,1 for x=0,1,2,3,4.at n=4A196862
- T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 3,4,2,0,1 for x=0,1,2,3,4.at n=59A196863
- T(n,k)=Number of nXk 0..4 arrays with each element x equal to the number of its horizontal and vertical neighbors equal to 3,4,2,0,1 for x=0,1,2,3,4.at n=61A196863
- The values of k in A220143.at n=35A220144
- Numbers k such that 1 + k + k^3 + k^5 + k^7 + k^9 + ... + k^49 is prime.at n=37A244388
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 141", based on the 5-celled von Neumann neighborhood.at n=21A270284