6445
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 19
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 7740
- Proper Divisor Sum (Aliquot Sum)
- 1295
- 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
- 5152
- Möbius Function
- 1
- Radical
- 6445
- 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
- 23
- 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 the continued fraction for sqrt(k) has period 23.at n=25A020362
- a(n) = s(n+3)/3, where s(n) = A024725(n).at n=14A024726
- T(2n,n-1), T given by A026659.at n=6A026661
- 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 8.at n=10A031421
- Numbers k such that k concatenated with k 1's is a prime.at n=18A068817
- Frobenius number of the numerical semigroup generated by three consecutive pentagonal numbers.at n=10A069757
- Minimal positive solution a(n) of Diophantine equation a(n)^2 - a(n)*b(n) - G(n)*b(n)^2 = +1 or -1 with G(n) := A078358(n). The companion sequence is b(n)=A077058(n).at n=58A077057
- Number of even parts in all partitions of n into distinct parts.at n=47A116680
- Sum of parts, counted without multiplicities, in all partitions of n into odd parts.at n=30A116930
- Number of digits in the decimal expansion of the number of partitions of 2^n.at n=25A129490
- Numbers k such that continued fraction of (1 + sqrt(k))/2 has period 11.at n=29A146335
- 2-comma numbers: n occurs in the sequence S[k+1] = S[k] + 10*last_digit(S[k-1]) + first_digit(S[k]) for two different splittings n=concat(S[0],S[1]).at n=34A166512
- a(n) = 5*n^2 - n + 1.at n=36A172043
- Iterative mapping with offset: a(1)=46465694290, a(n)=A095904(a(n-1)-2).at n=2A179227
- a(n) = a(n-2)+a(n-4); a(1)=a(4)=101, a(2)=a(3)=10.at n=22A180236
- G.f.: exp( Sum_{n>=1} (x^n/n)/sqrt(1 - 2*(2*x)^n) ).at n=8A184512
- Odd numbers producing 5 odd numbers in the Collatz iteration.at n=34A198588
- Number of partitions of n into terms of (1,4)-Ulam sequence, cf. A003666.at n=54A199120
- Number of 0..n arrays x(0..9) of 10 elements with zero 4th differences.at n=47A200372
- Semiprimes p such that next semiprime after p is p + 10.at n=25A217030