13655
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 20
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 16392
- Proper Divisor Sum (Aliquot Sum)
- 2737
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 10920
- Möbius Function
- 1
- Radical
- 13655
- 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
- 182
- 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
- a(n) = ceiling((1 + sum of preceding terms) / 2) starting with a(0) = 1.at n=24A005428
- Odd composite numbers which in base 2 contain their largest proper factor as a substring of digits.at n=25A063131
- a(n) = ceiling((Sum_{k=1..n-1} a(k)) / 2) for n >= 2 starting with a(1) = 1.at n=25A073941
- Numerator of the generalized harmonic number H(n,5,3).at n=4A075141
- Subsequence of A005428 where state = 2.at n=12A081615
- Numbers n such that A003313(3n) < A003313(n).at n=4A104699
- a(1) = 1; for n > 1: if n is even, a(n) = least k > 0 such that sum(i=1,n/2,a(2*i-1))/sum(j=1,n,a(j))>=1/4, or 1 if there is no such k; if n is odd, a(n) = largest k > 0 such that sum(i=1,(n+1)/2,a(2*i-1))/sum(j=1,n,a(j))<=1/3, or 1 if there is no such k.at n=52A104740
- Numbers with at least two odd prime factors (not necessarily distinct) such that in binary representation all divisors of n are contained in n.at n=10A105442
- Numbers k such that A003313(k) = A003313(6*k).at n=4A116461
- Partial sums of A003325.at n=38A139211
- The length of Sapro's necklace at successive years in Werneck's Black Pearl Necklace problem.at n=21A140261
- Inverse binomial transform of A140359.at n=14A140360
- Numbers n such that 6n and 12n are both the average of twin prime pairs.at n=26A177680
- Numbers k such that 3^k + 22 is prime.at n=21A219042
- Number of nX3 0..2 arrays with no more than floor(nX3/2) elements equal to at least one horizontal, diagonal or antidiagonal neighbor, with new values introduced in row major 0..2 order.at n=3A222997
- T(n,k)=Number of nXk 0..2 arrays with no more than floor(nXk/2) elements equal to at least one horizontal, diagonal or antidiagonal neighbor, with new values introduced in row major 0..2 order.at n=18A223000
- Number of 4Xn 0..2 arrays with no more than floor(4Xn/2) elements equal to at least one horizontal, diagonal or antidiagonal neighbor, with new values introduced in row major 0..2 order.at n=2A223003
- Numbers ((binomial(4*p-1,2*p-1) mod p^5)-3)/p^3, where p = prime(n).at n=36A224952
- Number of partitions of 10 copies of n into distinct parts.at n=9A258288
- Palindromic numbers in bases 4 and 7 written in base 10.at n=11A259378