1781
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 1932
- Proper Divisor Sum (Aliquot Sum)
- 151
- 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
- 1632
- Möbius Function
- 1
- Radical
- 1781
- 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
- 73
- 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
- Smallest nonnegative number that is the sum of 3 squares in exactly n ways.at n=17A000437
- Smallest number that is the sum of 3 squares in at least n ways.at n=17A000451
- Squares written in base 9.at n=36A002442
- Numbers that are the sum of 10 positive 6th powers.at n=26A003366
- Coordination sequence T1 for Zeolite Code AFR.at n=32A008019
- Coordination sequence T1 for Zeolite Code LAU.at n=30A008124
- Coordination sequence T1 for Zeolite Code MEL.at n=27A008150
- Numbers k such that the continued fraction for sqrt(k) has period 9.at n=17A010339
- a(n) = n*(21*n + 1)/2.at n=13A022279
- Place where n-th 1 occurs in A023119.at n=36A022781
- Numbers with exactly 5 2's in their ternary expansion.at n=34A023703
- a(n) = floor((3rd elementary symmetric function of 2,3,...,n+3)/(2+3+...+n+3)).at n=11A024178
- Least sum of 3 distinct nonzero squares in exactly n ways.at n=15A025415
- Number of partitions of n into an odd number of parts, the least being 6; also, a(n+6) = number of partitions of n into an even number of parts, each >=6.at n=69A027192
- Numbers k such that the continued fraction for sqrt(k) has odd period and if the last term of the periodic part is deleted then there are a pair of central terms both equal to 3.at n=22A031416
- Fractional part of square root of a(n) starts with 2: first term of runs.at n=39A034108
- Coordination sequence Z12 for Zeolite Code STT.at n=28A038416
- Coordination sequence T1 for Zeolite Code STT.at n=28A038428
- Coordination sequence T1 for Zeolite Code SFF.at n=28A038437
- Numbers whose base-12 representation has the same nonzero number of 0's and 5's.at n=44A039497