7801
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 8100
- Proper Divisor Sum (Aliquot Sum)
- 299
- 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
- 7504
- Möbius Function
- 1
- Radical
- 7801
- 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
- 145
- 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
- a(n) = 9*a(n-1) + 5*a(n-2).at n=5A015581
- Numbers k such that the continued fraction for sqrt(k) has period 67.at n=9A020406
- a(n) = (d(n)-r(n))/5, where d = A026057 and r is the periodic sequence with fundamental period (1,0,3,1,0).at n=54A026059
- Number of partitions of n with equal nonzero number of parts congruent to each of 0 and 1 (mod 3).at n=46A035537
- Base-4 digits are, in order, the first n terms of the periodic sequence with initial period 1,3,2.at n=6A037611
- Base-7 palindromes that start with 3.at n=28A043017
- Numbers k such that n | sigma_10(k) + phi(k)^10.at n=9A055704
- Centered 10-gonal numbers.at n=39A062786
- Centered 24-gonal numbers.at n=25A069190
- a(n) = (concatenation in ascending order of divisors of 2^n)/2^n.at n=4A077352
- a(n) = A078218(n)/n.at n=15A078810
- Main diagonal of square array A082025.at n=47A082189
- Pell pseudoprimes: odd composite numbers n such that P(n)-Kronecker(2,n) is divisible by n.at n=15A099011
- Numbers in base 10 that are palindromic in bases 7 and 8.at n=14A099145
- Matrix square-root of triangle A105615.at n=40A105623
- a(n) = Sum[2^(A047260(i)-1), {i,1,n}].at n=8A113828
- a(n) = 200*n + 1.at n=38A157956
- a(n) = 78*n^2 + 1.at n=10A158769
- a(n) = 1 + n*(n+1)*(n-1)/2.at n=25A158842
- a(n) = 8*n^2 + 20*n + 1.at n=30A161617