13561
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 13824
- Proper Divisor Sum (Aliquot Sum)
- 263
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 13300
- Möbius Function
- 1
- Radical
- 13561
- 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
- 89
- 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
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 72 ones.at n=16A031840
- Positions of 4-digit terms in the continued fraction for Pi (3 is at position 0).at n=14A048959
- Number of up-down involutions of length n.at n=15A072187
- Numbers n such that sum of squares of even digits of n equals sum of squares of odd digits of n.at n=14A076164
- Initial terms associated with the arithmetic progressions in A086786.at n=14A087308
- Leading entries in triangle in A090548 and A113470.at n=14A090547
- a(n) = sum of n-th column in array in A100452.at n=24A100454
- Numbers k such that 2*10^k+9 is prime.at n=7A101392
- Sum of digits of (2^(10^n)).at n=4A101429
- 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, 1), (-1, 1, -1), (1, -1, 1), (1, 0, 0)}.at n=11A148036
- Number of partitions of 12*n into parts < 5.at n=10A191593
- The least nonsquare number s having exactly n twos in the periodic part of the continued fraction of sqrt(s).at n=37A206582
- Number of n-bead necklaces labeled with numbers -5..5 not allowing reversal, with sum zero and first and second differences in -5..5.at n=7A209004
- T(n,k) = number of n-bead necklaces labeled with numbers -k..k not allowing reversal, with sum zero and first and second differences in -k..k.at n=73A209007
- Smallest semiprime (A001358) which is at the beginning of an arithmetic progression of n semiprimes whose largest term is as small as possible.at n=14A226834
- Number of partitions of 4n into 4 parts.at n=30A238340
- Number of partitions of 3n into at most 4 parts.at n=40A256524
- Number of partitions of n*(n+1)*(n+2) into parts that are at most n.at n=4A258297
- a(n) = 11*a(n - 1) - 3*a(n - 2) for n>1, a(0)=0, a(1)=1.at n=5A268344
- Number of partitions of n*(n-1)/2 into at most four parts.at n=15A274099