9215
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 11760
- Proper Divisor Sum (Aliquot Sum)
- 2545
- 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
- 6912
- Möbius Function
- -1
- Radical
- 9215
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 3
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
- 153
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- Number of chessboard polyominoes with n squares.at n=9A001933
- Pseudoprimes to base 96.at n=31A020224
- Denominators of continued fraction convergents to sqrt(287).at n=6A041541
- Expansion of (1+x^2-x^3)/((1-x)*(1-2*x)).at n=12A052996
- Nonprimes m such that phi(m)*sigma(m) is divisible by m+1.at n=35A065148
- Nonprime solutions to k == -1 (mod phi(k+1)).at n=32A067930
- Least m which can be written as i*j+i+j in n different ways: A072670(m)=n.at n=16A072671
- Number of subwords UHH...HD in all peakless Motzkin paths of length n+3, where U=(1,1), D=(1,-1) and H=(1,0).at n=10A089742
- Index of first occurrence of n-th prime in A001203, the continued fraction for Pi.at n=19A107892
- a(n) = 9*4^n - 1.at n=5A114569
- Numbers k such that digit sum of 3^k is a power of 3.at n=28A118872
- Positive numbers of the form 4*n^2 - 1 which are not semiprimes.at n=39A123754
- Odd interprimes divisible by 19.at n=24A126231
- 2*A007318^(2) - A000012.at n=47A132307
- a(0)=a(1)=1; for n>1, a(n) = 2*a(n-1) + 1 if a(n-1) and n are coprime, otherwise a(n) = a(n-1)/gcd(a(n-1),n).at n=24A133580
- a(n) = 9*n^2-1.at n=31A136016
- a(n) = 36n^2 - 1.at n=15A136017
- a(n) = 16n^2 + 32n + 15.at n=23A141759
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, 0), (-1, 0, 0), (-1, 1, 0), (0, 0, 1), (1, 0, -1)}.at n=10A148284
- Composites c where |c-m| = 1, where m is any of the smallest positive integers with their number of divisors. (m belongs to sequence A007416.)at n=37A152246