7521
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
- 8
- Divisor Sum
- 10560
- Proper Divisor Sum (Aliquot Sum)
- 3039
- 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
- 4752
- Möbius Function
- -1
- Radical
- 7521
- Omega Function (Ω)
- 3
- 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
- 44
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
Appears in sequences
- Coefficients of modular function G_3(tau).at n=40A005761
- a(n) = a(n-1) + a(round(2*(n-1)/3)) + a(round((n-1)/3)) with a(1)=1, a(2)=2.at n=30A033500
- Indices of hexagonal numbers which are also octagonal.at n=2A046191
- Numbers k that divide 2^(k+3) - 1.at n=34A069927
- Records in the Conway's alimentary function A070871.at n=42A070926
- Numbers n with following property: suppose n^2 = d1 d2 d3 ...dk in decimal; then d1! + d2! + ... + dk! is a square.at n=46A089185
- Triangle read by rows: T(n,k) is number of peakless Motzkin paths of length n and having k UHH...HD's starting above level 0, where U=(1,1), H=(1,0) and D=(1,-1) (can be easily expressed using RNA secondary structure terminology).at n=33A098073
- a(1) = 3, a(n) = least k such that concatenation of n copies of k with all previous concatenation gives a prime.at n=45A111473
- The maximum integer dimension in which the volume of the hypersphere of radius n remains larger than 1.at n=20A177677
- Number of (w,x,y,z) with all terms in {0,...,n} and 2w=max{w,x,y,z}-min{w,x,y,z}.at n=25A212757
- Total number of parts of multiplicity 9 in all partitions of n.at n=39A222709
- Partial sums of A160239.at n=33A245542
- Number of (n+1) X (6+1) 0..1 arrays with every 2 X 2 subblock antidiagonal maximum minus diagonal minimum nondecreasing horizontally and diagonal maximum minus antidiagonal minimum nondecreasing vertically.at n=11A253395
- Number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 229", based on the 5-celled von Neumann neighborhood.at n=45A270946
- E.g.f. C(x) + S(x), such that C(x)^2 - S(x)^2 = 1, 3*C(x)^2 - 2*D(x)^3 = 1, and D(x) = 1 + Integral S(x)*C(x) dx.at n=8A278749
- E.g.f. C(x) = 1 + Integral S(x)*D(x)^2 dx, where C(x)^2 - S(x)^2 = 1 and 3*C(x)^2 - 2*D(x)^3 = 1.at n=4A278751
- Least number x such that x^n has n digits equal to k. Case k = 8.at n=16A285455
- Sum of the fourth largest parts in the partitions of n into 5 parts.at n=45A308824
- Number of normal patterns matched by integer partitions of n.at n=18A335837
- Positions in Pi where the leader in the race of digits changes.at n=36A361434