7747
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
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 7936
- Proper Divisor Sum (Aliquot Sum)
- 189
- 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
- 7560
- Möbius Function
- 1
- Radical
- 7747
- 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
- 52
- 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 7*4^k + 1 is prime.at n=23A002255
- Numerators of continued fraction convergents to sqrt(310).at n=9A041584
- Numbers having three 7's in base 10.at n=18A043519
- Counterbalanced numbers: Composite numbers k such that phi(k)/(sigma(k)-k) is an integer.at n=13A055940
- Prefixing, suffixing or inserting a 7 in the number anywhere gives a prime.at n=44A069832
- Duplicate of A055940.at n=13A070158
- Trisection of A007294.at n=32A073472
- Composite numbers k such that the continued fraction for k/m contains no 2 for any 1 <= m <= k.at n=26A082409
- Triangle, read by rows, such that the convolution of each row with {1,2} produces a triangle which, after the main diagonal is divided by 2 and the triangle is flattened, equals this flattened form of the original triangle.at n=56A092689
- Near-repdigit semiprimes with 7 as repeated digit.at n=15A105988
- a(1) = 1; for n > 1, a(n) is the least k > a(n-1) such that a(n) + a(n-1) is square and a(n) - a(n-1) is prime.at n=19A108972
- a(1) = 1 then the least multiple of odd numbers not odd multiples of 5, (3,7,9,11,13,17,19,21,23,27,29,...) such that every partial concatenation is noncomposite.at n=24A110433
- Numbers whose square is the concatenation of two numbers k and k+8.at n=0A115440
- Numbers with composite sum of digits and prime sum of cubes of digits.at n=40A121642
- Numbers k such that 10*(10^(k+1) + 10^k - 1) + 7 is prime.at n=18A123368
- Number of walks within N^3 (the first octant of Z^3) starting at (0,0,0) and consisting of n steps taken from {(-1, -1, -1), (-1, 0, 0), (0, -1, 1), (0, 0, 1), (1, 1, -1)}.at n=9A148403
- The trisection A178242(3n+2).at n=40A178370
- a(n) = (3*n+7)*(3*n+2)/2.at n=40A179436
- Composite numbers and 1 which yield a prime whenever a 7 is inserted anywhere in them, including at the beginning or end.at n=28A216168
- Semiprimes whose decimal representation has only digits in {4,5,7}.at n=33A217124