16121
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 11
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 19200
- Proper Divisor Sum (Aliquot Sum)
- 3079
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 13524
- Möbius Function
- 0
- Radical
- 329
- Omega Function (Ω)
- 4
- 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
- 97
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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 n-node trees of height at most 5.at n=14A001385
- Composite numbers whose prime factors contain no digits other than 4 and 7.at n=7A036318
- Negative numbers written in a bits-of-Pi/primorial base system.at n=28A109839
- a(n) = 8 + floor((2 + Sum_{j=1..n-1} a(j))/4).at n=34A120166
- a(n) = (n-1)*(n+4)*(n+6)/6 for n > 1, a(1)=1.at n=42A137742
- Number of different n X n symmetric matrices with nonnegative entries summing to 4. Also number of symmetric oriented graphs with 4 arcs on n points.at n=14A139594
- Number of n X n binary arrays symmetric under 180 degree rotation with all ones connected only in a 01000-11111-01000 pattern in any orientation.at n=11A147026
- Diagonal sums of number triangle A113582.at n=26A154324
- Number of (n+1)X(3+1) 0..2 arrays x(i,j) with every row sum{j*x(i,j), j=1..3+1} equal, and every column sum{i*x(i,j), i=1..n+1} equal.at n=7A232611
- T(n,k) is the number of (n+1) X (k+1) 0..2 arrays x(i,j) with every row Sum_{j=1..k+1} j*x(i,j) equal, and every column Sum_{i=1..n+1} i*x(i,j) equal.at n=47A232614
- T(n,k) is the number of (n+1) X (k+1) 0..2 arrays x(i,j) with every row Sum_{j=1..k+1} j*x(i,j) equal, and every column Sum_{i=1..n+1} i*x(i,j) equal.at n=52A232614
- Integers k such that 19*(10^k) + 1 is prime.at n=22A267420
- Numbers k that end with ( sum of digits of k )^2.at n=21A270343
- Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 643", based on the 5-celled von Neumann neighborhood.at n=6A273313
- Number of active (ON, black) cells at stage 2^n-1 of the two-dimensional cellular automaton defined by "Rule 705", based on the 5-celled von Neumann neighborhood.at n=6A273418
- a(n) = (n-4)*(n+1)*(n+3)/6.at n=42A275874
- Fully multiplicative with a(prime(k)) = Lucas(2*(k+1)) for k-th prime p, where Lucas(n) = A000032(n).at n=39A324900
- Odd composite integers m such that A004187(2*m-J(m,45)) == J(m,45) (mod m) and gcd(m,45)=1, where J(m,45) is the Jacobi symbol.at n=35A340124
- Number of integer partitions of n such that (maximum) <= 2*(median).at n=48A361848
- E.g.f. A(x) satisfies A(x) = exp(x*B(x*A(x))), where B(x) = 1 + x*B(x)^3 is the g.f. of A001764.at n=5A382015