7555
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 22
- Digital Root
- 4
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 9072
- Proper Divisor Sum (Aliquot Sum)
- 1517
- 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
- 6040
- Möbius Function
- 1
- Radical
- 7555
- 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
- 132
- 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) = a(n-1) - 2*a(n-2) with a(0) = 2, a(1) = 1.at n=27A002249
- Numbers k such that the continued fraction for sqrt(k) has period 60.at n=39A020399
- Composite numbers whose prime factors contain no digits other than 1 and 5.at n=17A036305
- Numbers having three 5's in base 10.at n=33A043511
- a(n) = a(1) + a(2) + ... + a(n-1) - a(m) for n >= 4, where m = 2*n - 3 - 2^(p+1) and p is the unique integer such that 2^p < n - 1 <= 2^(p+1), starting with a(1) = a(2) = 1 and a(3) = 2.at n=15A049888
- Triangle T(n,k) is the number of restricted growth strings (RGS) of set partitions of {1..n} that have a decrease at index k (1<=k<n).at n=33A056862
- Composite n such that the sums of the composite numbers up to n, +/- 1, are twin primes.at n=38A065022
- a(n) is the unique odd positive solution y of 2^n = 7x^2 + y^2.at n=26A077021
- a(n) = floor(8^n/5^n).at n=19A094985
- Number of partitions of n in which every part occurs 1, 4, or 5 times. Also number of partitions of n in which every part is congruent to {1, 3, 4, 5, 7} mod 8.at n=46A100853
- Near-repdigit semiprimes with 5 as repeated digit.at n=25A105986
- Maximal number of squares of side 1 in an ellipse of semiaxes n,2n.at n=34A108126
- Numbers such that the digital sums in bases 2, 3, 5 and 7 all are equal.at n=9A135127
- Numbers k such that k and k^2 use only the digits 0, 2, 5, 7 and 8.at n=14A136916
- 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, 0), (-1, 1, -1), (0, 0, 1), (0, 1, -1), (1, -1, -1)}.at n=11A148011
- Number of primes between exponents of successive Mersenne primes.at n=31A157890
- Cubes (n * n * n) in carryless arithmetic mod 10.at n=35A169885
- Semiprimes whose decimal representation has only digits in {4,5,7}.at n=31A217124
- Numbers whose digits are prime and which retain this property when multiplied by some 1-digit prime (i.e., one of 2, 3, 5 or 7).at n=16A227922
- Composite numbers whose concatenation of their aliquot parts, in descending order, is a palindrome.at n=20A249301