7251
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 9672
- Proper Divisor Sum (Aliquot Sum)
- 2421
- 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
- 4832
- Möbius Function
- 1
- Radical
- 7251
- 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
- 70
- 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
- Expansion of e.g.f. arctan(log(x+1) - sinh(x)).at n=9A013261
- Expansion of e.g.f. tanh(log(x+1) - sinh(x)).at n=9A013265
- a(n) = 2nd elementary symmetric function of {1, prime(1), prime(2), ..., prime(n-1)}, where prime(0) = 1.at n=9A024522
- 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=3A031583
- Numerators of continued fraction convergents to sqrt(236).at n=6A041440
- Numerators of continued fraction convergents to sqrt(944).at n=8A042826
- Consider the Diophantine equation x^3 + y^3 = z^3 - 1 (x < y < z) or 'Fermat near misses'. Arrange solutions by increasing values of z. Sequence gives values of x.at n=28A050788
- Antidiagonal sums of square array A082011 divided by the number of the antidiagonal.at n=42A082015
- a(1) = 1 and then least squarefree number such that every partial concatenation of 2 or more terms is a prime.at n=42A086475
- Bisection of A088567.at n=51A088585
- Triangular sequence produced from symmetrical power of two matrices of the general type: M={{1, 2, 4, 8}, {2, 1, 2, 4}, {4, 2, 1, 2}, {8, 4, 2, 1}}.at n=33A129964
- Numbers k such that k and k^2 use only the digits 0, 1, 2, 5 and 7.at n=38A136824
- First differences of A006128.at n=27A138137
- a(n) = 196*n - 1.at n=36A158225
- Numbers n such that 2^x + 3^y is never prime when max(x,y) = n.at n=9A159625
- a(n) = Sum of all numbers of divisors of all numbers < (n+1)^2.at n=30A168011
- Smith numbers of order 2.at n=33A174460
- Number of nXnXn 0..6 triangular arrays with each element x equal to the number its neighbors equal to 5,0,0,0,2,1,0 for x=0,1,2,3,4,5,6.at n=4A198048
- a(n) = 6*a(n-1) - 9*a(n-2) + a(n-3), with a(0)=3, a(1)=6 and a(2)=18.at n=7A215455
- a(n) = 3*a(n-2) - a(n-3), with a(0)=3, a(1)=0, and a(2)=6.at n=14A215664