17391
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
- 4
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 27648
- Proper Divisor Sum (Aliquot Sum)
- 10257
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9600
- Möbius Function
- 1
- Radical
- 17391
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 4
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- yes
- 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
- 84
- 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
- Number of n-step walks on square lattice in the first quadrant which finish at distance n-3 from the x-axis.at n=30A005564
- Pseudoprimes to base 35.at n=35A020163
- a(n) = [ (3rd elementary symmetric function of S(n))/(first elementary symmetric function of S(n)) ], where S(n) = {first n+2 odd positive integers}.at n=16A024202
- Number of partitions of n into parts 3k+1 and 3k+2 with at least one part of each type.at n=47A035620
- Sum of antidiagonals of A060736.at n=31A061349
- Smallest triangular numbers that contain the digits of n anywhere in their middle.at n=39A062829
- a(n) = (2*n - 1)*(7*n^2 - 7*n + 3)/3.at n=15A063494
- Triangular numbers with sum of digits = 21.at n=14A068131
- Triangular numbers with property that swapping first and last digits also gives a triangular number.at n=40A069708
- Numbers n such that sum of distinct primes dividing n is divisible by the largest prime dividing n. Also n is neither a prime, nor a true power of prime and n is squarefree. Squarefree solutions of A071140.at n=20A071141
- Numbers n such that (i) the sum of the distinct primes dividing n is divisible by the largest prime dividing n and (ii) n has exactly 4 distinct prime factors and (iii) n is squarefree.at n=7A071143
- Squarefree numbers k such that the largest prime factor of k is equal to the sum of the other prime factors of k.at n=19A071312
- Concatenation of triangular number k and its 10's complement is prime.at n=13A108970
- Partial sums of dodecahedral numbers (A006566).at n=11A116689
- Triangular numbers for which the sum of the digits is an octagonal number.at n=17A117523
- Triangular numbers with only odd digits.at n=18A117960
- Lucky numbers for which both the sum of the digits and the product of the digits is also a lucky number.at n=36A118559
- Numbers which are both lucky and triangular.at n=33A118565
- Triangular numbers t which are average of two consecutive primes p and p+4.at n=21A129752
- Triangular numbers t such that t+10 is a prime.at n=27A129755