1969
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 25
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 2160
- Proper Divisor Sum (Aliquot Sum)
- 191
- 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
- 1780
- Möbius Function
- 1
- Radical
- 1969
- 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
- 24
- 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
- Numbers k such that (1,k) is "good".at n=21A000696
- Numbers k such that 25*4^k + 1 is prime.at n=23A002263
- An equivalence relation on permutations.at n=7A003510
- Odd numbers not of form p + 2^k (de Polignac numbers).at n=44A006285
- Shifts 2 places left when binomial transform is applied twice with a(0) = a(1) = 1.at n=8A007472
- Coordination sequence T2 for Zeolite Code -WEN.at n=32A009863
- a(n) = floor( n*(n-1)*(n-2)*(n-3)/29 ).at n=17A011939
- Six iterations of Reverse and Add are needed to reach a palindrome.at n=36A015984
- Numbers k such that the continued fraction for sqrt(k) has period 62.at n=1A020401
- Numbers k such that Fibonacci(k) == 89 (mod k).at n=27A023182
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = (Lucas numbers), t = A000201 (lower Wythoff sequence).at n=15A024474
- a(n) = s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = (Lucas numbers), t = A000201 (lower Wythoff sequence).at n=14A025094
- [ Sum (s(j) - s(i))^3 ], 1 <= i < j <= n, where s(k) = 1 + 1/2 + ... + 1/k.at n=38A025217
- Odd n such that in n^2 the parity of digits alternates.at n=49A030155
- Numbers whose base-10 representation has 2 fewer 0's than 9's.at n=38A031500
- Numbers k such that the period of the continued fraction for sqrt(k) contains exactly 20 ones.at n=25A031788
- Numbers k such that 21*2^k+1 is prime.at n=20A032360
- Number of partitions of n into parts not of the form 15k, 15k+2 or 15k-2. Also number of partitions with 1 part of size 1 and differences between parts at distance 6 are greater than 1.at n=30A035956
- Denominators of continued fraction convergents to sqrt(771).at n=10A042487
- Numbers having two 9's in base 10.at n=42A043526