13881
domain: N
Properties
Digital Properties
- Digit Count
- 5
- 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
- 21184
- Proper Divisor Sum (Aliquot Sum)
- 7303
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 7920
- Möbius Function
- -1
- Radical
- 13881
- 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
- 151
- 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
- The convergent sequence B_n for the ternary continued fraction (3,1;2,2) of period 2.at n=12A000963
- a(n) = n*(3*n^2 - 1)/2.at n=21A004188
- Expansion of g.f. 1/((1-x)*(1-2*x)*(1-10*x)).at n=4A016205
- 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 78.at n=34A031576
- Numbers k such that 179*2^k+1 is prime.at n=25A032466
- Numbers n such that n divides the (right) concatenation of all numbers <= n written in base 8 (most significant digit on right).at n=21A061937
- Interprimes (A024675) which are of the form s*prime, s=21.at n=29A075296
- List of codewords in binary lexicode with Hamming distance 6 written as decimal numbers.at n=21A075934
- Numbers k such that (k / sum of digits of k) and (k+1 / sum of digits of k+1) are both prime.at n=19A085775
- 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, 0, 0), (-1, 1, 1), (0, -1, 0), (0, 1, -1), (1, 0, 0)}.at n=9A148710
- Number of fixed 6-dimensional polycubes with n cells.at n=4A151832
- G.f.: (21+104*x+103*x^2+23*x^3+x^4)/(1-x)^5.at n=5A160787
- Position of 3^n in A051037 (5-smooth numbers).at n=41A188426
- Truncated octahedron with faces of centered polygons.at n=10A193228
- Row sums of an irregular triangle read by rows in which row n lists the next A026741(n+1) natural numbers A000027.at n=40A195309
- Number of partitions of 5n into exactly 4 parts.at n=25A256327
- Coefficients in expansion of 1/(1 + x - 2*x^5).at n=37A317509
- Indices n of Riemann zeta zeros where the Riemann-Siegel Z function sets successive records of maximum absolute values abs(Z(t)) in the interval between the n-th and (n+1)-th zeros.at n=35A329823
- Squarefree numbers k for which Q(k) - 6*k/Pi^2 sets a new record minimum, where Q(x) is the number of squarefree numbers up to x.at n=21A339865
- The sum of the numbers on straight lines of incrementing length n when drawn over numbers of the square spiral, where each line contains numbers which sum to the minimum possible value, and each number on the spiral can only be in one line. If two or more lines exist with the same sum the one containing the smallest number is chosen.at n=25A340974