7978
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 31
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 11970
- Proper Divisor Sum (Aliquot Sum)
- 3992
- 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
- 3988
- Möbius Function
- 1
- Radical
- 7978
- 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
- 52
- Smith Number
- yes
- 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
- yes
- Odd
- no
Appears in sequences
- Cycle class sequence c(n) (the number of true cycles of length n in which a certain node is included) for zeolite MEL = ZSM-11 Nan[AlnSi96-nO192] starting with a T4 atom.at n=12A019150
- Numbers k such that the continued fraction for sqrt(k) has period 41.at n=16A020380
- Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted then there are a pair of central terms both equal to 5.at n=40A031418
- Increasing gaps among twin primes: size.at n=39A036063
- Numerators of continued fraction convergents to sqrt(181).at n=5A041334
- Triangle T(n,k) of numbers of minimal 5-covers of an unlabeled n+5-set that cover k points of that set uniquely (k=5,..,n+5).at n=22A057968
- Indices k where A057176(k) = 4.at n=20A086838
- Start with {2} and close under the operations XY and XY+1; sequence gives complete list of numbers that do not appear.at n=93A093906
- Expansion of g.f. x*(x-1)*(x+1)^3/((2*x^3+x^2-1)*(x^4+1)).at n=24A107853
- G.f. satisfies: A(x) = 1 + Sum_{n>=1} x^(n-1)*series_reversion( x/A(x)^n ).at n=7A125224
- Similar to A072921 but starting with 2.at n=37A152231
- Number of 1..20 integer arrays v[1..n] of length n with all autocorrelation values sum(i){v[i]*v[i-k]} distinct for k in 0..n-1.at n=2A171294
- Number of 1..n integer arrays v[1..3] of length 3 with all autocorrelation values sum(i){v[i]*v[i-k]} distinct for k in 0..2.at n=19A171340
- Semiprimes that are the sum of 10 consecutive primes.at n=11A185347
- Number of 1 X (n+1) 0..1 arrays with every row least squares fitting to a positive-slope straight line and every column least squares fitting to a zero- or positive-slope straight line, with a single point array taken as having zero slope.at n=12A222970
- Smallest k such that k*2*p(n)^2-1=q is prime, k*2*q^2-1=r, k*2*r^2-1=s, k*2*r^2-1=t, r, s, and t are also prime.at n=20A224492
- Number of 3-separable partitions of n; see Comments.at n=52A239469
- Guttmann-Torrie simple cubic lattice series coefficients c_n^{22}(Pi/2).at n=8A259810
- a(n) begins the first chain of 9 consecutive positive integers of h-values with symmetrical gaps about the center, where h(k) is the length of the finite sequence k, f(k), f(f(k)), ...., 1 in the Collatz (or 3x + 1) problem.at n=36A268288
- Numbers whose smallest decimal digit is 7.at n=44A284068