9219
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 14080
- Proper Divisor Sum (Aliquot Sum)
- 4861
- 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
- 5256
- Möbius Function
- -1
- Radical
- 9219
- 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
- yes
- Harshad Number
- yes
- Narcissistic Number
- no
- Collatz Steps
- 47
- 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
- Numbers k where |cos(k)| (or |cosec(k)| or |cot(k)|) decreases monotonically to 0; also numbers k where |tan(k)| (or |sec(k)|, or |sin(k)|) increases.at n=31A004112
- Numbers that are the sum of 12 positive 10th powers.at n=9A004812
- Numbers k such that 4*3^k - 1 is prime.at n=17A005540
- a(n) = Sum_{j=1..n} j*prime(j).at n=19A014285
- Eleven iterations of Reverse and Add are needed to reach a palindrome.at n=34A015992
- Expansion of 1/((1-x)(1-3x)(1-5x)).at n=5A016209
- Least k such that tan(k) > tan(a(n-1)), for n >= 1, where a(0) = 0.at n=42A024814
- a(n) = position of n^3 + 9 in A003072.at n=43A024971
- 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 64.at n=18A031562
- Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 64.at n=2A031742
- Triangle of B-analogs of Stirling numbers of the second kind.at n=30A039755
- Triangle of B-analogs of Stirling numbers of 2nd kind.at n=33A039756
- Denominators of continued fraction convergents to sqrt(437).at n=7A041833
- Numbers whose base-5 representation contains exactly three 3's and two 4's.at n=26A045306
- Numbers k where cos(k) decreases monotonically to 0.at n=16A046957
- Numbers k where sin(k) increases monotonically to 1 (or cosec(k) decreases).at n=20A046959
- Numbers k such that floor(tan(k)) > floor(tan(m)) for all m < k.at n=39A063537
- Numbers which need eleven 'Reverse and Add' steps to reach a palindrome.at n=32A065216
- Chebyshev polynomials S(n-1,21) with Diophantine property.at n=4A092499
- Triangular matrix T, read by rows, that satisfies: SHIFT_LEFT(column 0 of T^((3*p-1)/3)) = (3*p-1)*(column p of T), or [T^((3*p-1)/3)](m,0) = (3*p-1)*T(p+m,p) for all m>=1 and p>=0.at n=41A107717