17639
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 26
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 18240
- Proper Divisor Sum (Aliquot Sum)
- 601
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 17040
- Möbius Function
- 1
- Radical
- 17639
- 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
- yes
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 79
- 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
- Number of parts in all partitions of all the numbers in {1,2,...,n} into distinct parts.at n=34A015724
- Convolution of (F(2), F(3), F(4), ...) and odd numbers.at n=15A023652
- When squared gives number composed just of the digits 1, 2, 3, 4.at n=27A061677
- Trajectory of n under the Reverse and Add! operation carried out in base 3 (presumably) does not reach a palindrome and (presumably) does not join the trajectory of any term m < n.at n=37A077405
- a(1) = 1, a(2) = 2; for n >= 2, a(n+1) = a(n) + sum of the unique prime factors of a(n).at n=20A096460
- a(1)=1, a(2)=2; for n >= 2, a(n+1) = a(n) + sum of prime factors of a(n).at n=34A096461
- Number of partitions of n into deficient numbers.at n=38A097797
- Number of partitions of the n-th deficient number into deficient numbers.at n=30A097799
- Numbers k such that either k or k+1 is divisible by the numbers from 1 to 10.at n=26A131663
- a(n) = 10*n^2 - 1.at n=41A158447
- a(n) = 40*n^2 - 1.at n=20A158598
- Numbers m such that m mod k is k-1 for all k = 2..9.at n=6A166931
- Molecular topological indices of the pan graphs.at n=31A192836
- a(n+1) is the sum of a(n) and the prime factors of a(n), counted with multiplicity. Start with a(0) = 3.at n=18A192896
- Number of nXnXn 0..6 triangular arrays with each element x equal to the number its neighbors equal to 6,4,2,0,2,0,2 for x=0,1,2,3,4,5,6.at n=5A205075
- Least number k such that k^n + n and k^n - n are both prime, or 0 if no such number exists.at n=29A239475
- Composite numbers for which the root mean square of proper divisors is an integer.at n=23A247135
- Expansion of Product_{k>=1} (1 + x^k)^A050985(k).at n=20A301596
- a(n) is the least k such that there are exactly n numbers i with A075254(i) = k.at n=10A346378