4521
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 6624
- Proper Divisor Sum (Aliquot Sum)
- 2103
- 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
- 2720
- Möbius Function
- -1
- Radical
- 4521
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 183
- 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
- Pseudoprimes to base 10.at n=20A005939
- Number of self-avoiding walks of any length from NW to SW corners of a grid or lattice with n rows and 3 columns.at n=8A006189
- Number of planted trees where non-root, non-leaf nodes an even distance from root are of degree 2.at n=15A007562
- cos(arcsin(arctan(x)))=1-1/2!*x^2+5/4!*x^4-109/6!*x^6+4521/8!*x^8...at n=4A012091
- exp(arcsinh(arctanh(x)))=1+x+1/2!*x^2+2/3!*x^3+5/4!*x^4+24/5!*x^5...at n=8A012254
- Pseudoprimes to base 41.at n=35A020169
- Pseudoprimes to base 100.at n=30A020228
- Generalized Catalan Numbers x^4*A(x)^2 -(1-x+x^4+x^5+x^6)*A(x) + 1 =0.at n=22A023429
- Convolution of natural numbers with Beatty sequence for tau^2 A001950.at n=20A023542
- Divisors of 99999999.at n=20A027890
- Lucky numbers with size of gaps equal to 18 (lower terms).at n=26A031900
- a(n) = n * prime(n).at n=32A033286
- a(n) = a(n-1) + a(floor(n/2)), a(1) = 1.at n=48A033485
- Numbers whose base-4 representation contains exactly three 1's and three 2's.at n=23A045103
- Number of nonnegative solutions of x1^2 + x2^2 + ... + x12^2 = n.at n=8A045853
- McKay-Thompson series of class 52A for Monster.at n=54A058705
- a(n) = (2*n-1)*(n^2 -n +2)/2.at n=16A063488
- Partial sums of A068058 + 1.at n=28A068059
- Least k such that Sum_{i=1..k} (prime(i) + prime(i+2) - 2*prime(i+1)) = 2n + 1.at n=29A073051
- Subminimal numbers, from minimal numbers by analogy with subfactorials.at n=39A079717