7999
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 34
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 8440
- Proper Divisor Sum (Aliquot Sum)
- 441
- 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
- 7999
- 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
- 189
- 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
- a(n) = n*(7*n^2 - 1)/6.at n=19A004126
- Numerators of worst case for Engel expansion.at n=34A006539
- Pseudoprimes to base 20.at n=29A020148
- Strong pseudoprimes to base 20.at n=7A020246
- Sums of distinct powers of 6.at n=43A033043
- Positive numbers having the same set of digits in base 2 and base 6.at n=39A037411
- Sums of 4 distinct powers of 6.at n=6A038480
- Gaps of 7 in sequence A038593 (upper terms).at n=24A038654
- Numbers ending with '9' that are the difference of two positive cubes.at n=28A038864
- Denominators of continued fraction convergents to sqrt(491).at n=9A041937
- Numbers having four 1's in base 6.at n=26A043376
- Numbers having three 9's in base 10.at n=7A043527
- Numbers whose base-5 representation contains exactly two 2's and three 4's.at n=30A045288
- Smallest number whose sum of digits is n.at n=34A051885
- Smallest number with digit sum = Fibonacci(n).at n=9A061249
- Smallest composite number with digit sum n.at n=33A067524
- a(n) = n^3 - 1.at n=19A068601
- a(n) is the smallest composite number with the sum of digits = the n-th composite number.at n=21A073866
- a(n) = smallest k such that 5k has a digit sum = n.at n=34A077492
- a(n) equals the coefficient of x^n in f(x)^n where f(x)=1+sum(n>=0,x^(2^n)).at n=9A088704