7814
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 11724
- Proper Divisor Sum (Aliquot Sum)
- 3910
- 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
- 3906
- Möbius Function
- 1
- Radical
- 7814
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 39
- 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
- yes
- Odd
- no
Appears in sequences
- a(n) = 2^n - C(n,0) - C(n,1) - C(n,2) - C(n,3).at n=13A002663
- From Engel product expansion of 4/7.at n=13A007768
- a(n) = Sum_{k=0..9} binomial(n,k).at n=13A008862
- a(n) is the sum of the non-Fibonacci numbers in row n of array T given by A027935, computed as T(n,m) + T(n,m+1) + ... + T(n,n-1), where m = floor((n+2)/2).at n=13A027946
- 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 88.at n=3A031586
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 48 ones.at n=22A031816
- a(n) = Sum_{i=1..n} T(i,n-i), where T is A049615.at n=46A049616
- Binomial transform of A064413.at n=10A065971
- Semiprimes of the form 2*(m^2 + m + 1) (implying that m^2 + m + 1 is a prime).at n=21A107317
- Semiprimes (A001358) whose digit reversal is a pentagonal number (A000326).at n=19A115708
- Numbers k such that A118255(k) is prime.at n=17A118257
- a(1) = a(2) = 1. a(n) = a(n-1) + (largest noncomposite {1 or prime} among the first n-2 terms of the sequence).at n=27A120761
- a(n) = (5^n + 3)/2.at n=6A132079
- Indices for which A097344 differs from A097345.at n=2A134652
- Numbers whose square is a permutational number A134640.at n=25A134742
- a(n) = 2^(floor((n-1)/2)) - n*(n-1)/2.at n=27A163417
- Sequence defined by the recurrence formula a(n+1)=sum(a(p)*a(n-p)+k,p=0..n)+l for n>=1, with here a(0)=1, a(1)=0, k=0 and l=-1.at n=13A176675
- Triangle read by rows: T(n,k) is the number of permutations of [n] that have k isolated entries (0 <= k <= n).at n=48A180196
- Number of distinct solutions of sum{i=1..2}(x(2i-1)*x(2i)) = 1 (mod n), with x() only in 2..n-2.at n=42A180825
- Table T(m,n) = (5^m + 3^n)/2, m,n = 0,1,2,..., read by antidiagonals.at n=34A193770