6981
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 24
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 10080
- Proper Divisor Sum (Aliquot Sum)
- 3099
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 4272
- Möbius Function
- -1
- Radical
- 6981
- 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
- no
- Harshad Number
- no
- Narcissistic Number
- no
- Collatz Steps
- 150
- Smith Number
- yes
- 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
- Crystal ball sequence for D_5 lattice.at n=4A008356
- Numbers k that divide the (left) concatenation of all numbers <= k written in base 19 (most significant digit on left).at n=34A029488
- Numbers k such that 21*2^k+1 is prime.at n=26A032360
- Take the first n numbers written in base 4, concatenate them, then convert from base 4 to base 10.at n=4A048436
- Numbers n such that 97*2^n-1 is prime.at n=8A050574
- The first n digits of the juxtaposition of the base-4 numbers converted to decimal.at n=6A055145
- Numbers n such that n divides the (left) concatenation of all numbers <= n written in base 16 (most significant digit on right).at n=11A061969
- Second 11-gonal (or hendecagonal) numbers: a(n) = n*(9*n+7)/2.at n=39A062728
- a(1)=0, and a(n+1) is the position of first occurrence of a(n) in the decimal expansion of 1/Pi.at n=9A098319
- Records in A007535.at n=22A098654
- Square array, read by antidiagonals, where row n equals the crystal ball sequence for D_n lattice.at n=49A108553
- Least number d such that 10^n -/+ d form a prime pair.at n=47A115564
- Numbers k such that L(2*k + 1) is prime, where L(m) is a Lucas number.at n=30A117522
- an=n-th smallest integer m=p1*p2*p3, product of 3 odd primes such that d+2m/d are all primes for d dividing 2m.at n=8A128278
- Column 2 of triangle A128545; a(n) is the coefficient of q^(2n+4) in the central q-binomial coefficient [2n+4,n+2].at n=14A128552
- Number of distinct means of nonempty subsets of {1,...,n}.at n=40A135342
- Partial sums of A007694.at n=32A174030
- y value of the local maximum of a discrete plot of the result of concatenating the integers one to n in base x.at n=3A175916
- Array read by antidiagonals: row b lists the base-b analog of the base-10 sequence 1, 12, 123, ..., 123456789, 12345678910, ... (A007908).at n=32A179069
- Parameters n for which the Tate-Shafarevich group Ш of the elliptic curve y^2=x^3-n has order 16.at n=33A179140