7491
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
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 10944
- Proper Divisor Sum (Aliquot Sum)
- 3453
- 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
- 4520
- Möbius Function
- -1
- Radical
- 7491
- 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
- 163
- 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
- a(n) = n*(31*n-1)/2.at n=22A022288
- a(n) = least m such that if r and s in {1/2, 1/5, 1/8, ..., 1/(3n-1)} satisfy r < s, then r < k/m < (k+1)/m < s for some integer k.at n=38A024837
- a(n) = (d(n)-r(n))/2, where d = A026037 and r is the periodic sequence with fundamental period (1,0,0,1).at n=33A026038
- Euler transform of 5 4 3 2 1 1 1 1 1 1 1 ...at n=9A029861
- 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 85.at n=24A031583
- a(n) = a(n-1) + a(m) for n >= 4, where m = 2^(p+1) + 2 - n and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = 1, a(2) = 2, and a(3) = 4.at n=43A050053
- Integers n > 879 such that the 'Reverse and Add!' trajectory of n joins the trajectory of 879.at n=37A063052
- prime(2n) + prime(n) == 0 (mod n).at n=16A066896
- Sum of the remainders when n^2 is divided by squares less than n.at n=37A067459
- Number of partitions of n into Lucas parts (A000032).at n=53A067593
- Expansion of (1-x)^(-1)/(1+x-2*x^2+2*x^3).at n=12A077900
- Partial sums of A080180.at n=19A080181
- a(n) = 6*n^2 + 4*n + 1.at n=35A080859
- Beginning with 1, numbers such that the differences a(k)-a(k-1) are distinct and every concatenation n>1 is prime.at n=40A090504
- Structured snub cubic numbers.at n=10A100150
- Equatorial structured meta-anti-diamond numbers, the n-th number from an equatorial structured n-gonal anti-diamond number sequence.at n=10A100189
- a(n) is the number of positive integers <= 10^n that are divisible by no prime exceeding 3.at n=46A100752
- T(n,k) = 12*A046802(n,k) - 9*A008518(n,k) - 2*A007318(n,k), triangle read by rows (0 <= k <= n).at n=33A168293
- T(n,k) = 12*A046802(n,k) - 9*A008518(n,k) - 2*A007318(n,k), triangle read by rows (0 <= k <= n).at n=30A168293
- Coefficient of x in the reduction by x^2 -> x+1 of the polynomial p(n,x) defined at Comments.at n=14A192389