7571
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
- 7752
- Proper Divisor Sum (Aliquot Sum)
- 181
- 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
- 7392
- Möbius Function
- 1
- Radical
- 7571
- 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
- 132
- 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(0) = 1, a(n) = 9*n^2 + 2 for n>0.at n=29A010002
- Apply partial sum operator 4 times to partition numbers.at n=12A014161
- 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 87.at n=0A031585
- Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 87.at n=0A031765
- Numbers n such that A003313(n) = A003313(2n).at n=27A086878
- Start with 1015 and repeatedly reverse the digits and add 4 to get the next term.at n=28A117807
- Number of n X n binary arrays symmetric under 90 degree rotation with all ones connected only in a 1000-1000-1111-0010 pattern in any orientation.at n=14A147113
- a(n) = 4*n*(n+1) + 3.at n=43A164897
- Numbers that are the product of two distinct primes a and b, such that a^3+b^3 is the average of a twin prime pair.at n=27A176876
- Row sums of A181851.at n=11A181849
- Number of 4 X n arrays of the minimum value of corresponding elements and their horizontal or diagonal neighbors in a random, but sorted with lexicographically nondecreasing rows and nonincreasing columns, 0..1 4 X n array.at n=33A220034
- T(n,k)=Number of ways to reciprocally link elements of an nXk array either to themselves or to exactly two horizontal, diagonal or antidiagonal neighbors.at n=46A220725
- Number of ways to reciprocally link elements of a 2 X n array either to themselves or to exactly two horizontal, diagonal or antidiagonal neighbors.at n=8A220726
- Number of compositions of n such that the first part is 1 and the second differences of the parts are in {-9,...,9}.at n=15A239559
- Number of nX3 0..1 arrays with no element equal to the same number of vertical neighbors as horizontal neighbors, with new values 0..1 introduced in row major order.at n=10A240644
- Number of partitions of n with difference 6 between the number of odd parts and the number of even parts, both counted without multiplicity.at n=34A242697
- Semiprimes whose prime factors are of equal binary length and which differ from each other in exactly three bit positions.at n=15A261075
- Number T(n,k) of permutations of [n] with exactly k (possibly overlapping) occurrences of the consecutive pattern 1324; triangle T(n,k), n>=0, 0<=k<=max(0,floor(n/2-1)), read by rows.at n=15A264173
- Number of permutations of [n] with exactly one occurrence of the consecutive pattern 1324.at n=4A264174
- Partial sums of the number of active (ON, black) cells in n-th stage of growth of two-dimensional cellular automaton defined by "Rule 73", based on the 5-celled von Neumann neighborhood.at n=21A270089