7149
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
- 4
- Divisor Sum
- 9536
- Proper Divisor Sum (Aliquot Sum)
- 2387
- 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
- 4764
- Möbius Function
- 1
- Radical
- 7149
- Omega Function (Ω)
- 2
- Little Omega Function (ω)
- 2
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
- 49
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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
- 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=20A031554
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 50 ones.at n=21A031818
- Becomes prime or 4 after exactly 8 iterations of f(x) = sum of prime factors of x.at n=21A048130
- Integers n > 7059 such that the 'Reverse and Add!' trajectory of n joins the trajectory of 7059.at n=0A063058
- (-1)^n * coefficient of x^n in 1/x-1/(1-eta(x)) power series.at n=24A082531
- Triangle read by rows: T(n,k) (0<=k<=n) is the number of Schroeder paths of length 2n, having k (1,0)-steps on the lines y=0 and y=1 (a Schroeder path of length 2n is a path from (0,0) to (2n,0), consisting of steps U=(1,1), D=(1,-1) and H=(2,0) and never going below the x-axis).at n=50A110189
- Potential magic constants of 7 X 7 magic squares composed of consecutive primes.at n=18A188536
- Fourth-order spt function.at n=10A221142
- Number of length n 0..2 arrays with each partial sum starting from the beginning no more than one standard deviation from its mean.at n=9A244782
- Smallest number m such that the n-th prime is the median prime factor of 1..m, cf. A212300.at n=36A246430
- Integers k such that k^2 + 1 = 2*p where p and p+2 are twin primes.at n=46A261542
- Number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 203", based on the 5-celled von Neumann neighborhood.at n=45A270725
- Odd numbers k such that phi(k) and cototient(k) have the same prime signature.at n=9A280927
- Expansion of e.g.f. Product_{k>=1} (1 + (exp(x) - 1)^k/k!).at n=7A305547
- Numerators of the partial alternating sums of the reciprocals of the sum of unitary divisors function (A034448).at n=26A379515
- Square array A(n,k), n >= 0, k >= 0, read by antidiagonals downwards, where column k is the expansion of B(x)^k, where B(x) is the g.f. of A381568.at n=34A381567
- G.f. A(x) satisfies A(x) = (1 + x*A(x*A(x)))^2.at n=6A381568
- Integers k that are equal to the sum of at least two distinct of their anagrams, which must have the same number of digits as k.at n=33A384433