7920
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 60
- Divisor Sum
- 29016
- Proper Divisor Sum (Aliquot Sum)
- 21096
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 1920
- Möbius Function
- 0
- Radical
- 330
- Omega Function (Ω)
- 8
- Little Omega Function (ω)
- 4
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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 101
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- 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
- yes
- Odd
- no
Appears in sequences
- Order of the group SL(2,Z_n).at n=21A000056
- Let A(n) = #{(i,j): i^2 + j^2 <= n}, V(n) = Pi*n, P(n) = A(n) - V(n); sequence gives values of n where |P(n)| sets a new record.at n=33A000099
- Orders of noncyclic simple groups (without repetition).at n=14A001034
- Orders of sporadic simple groups.at n=0A001228
- High temperature series for spin-1/2 Heisenberg susceptibility on 3-dimensional simple cubic lattice.at n=3A002170
- Theta series of D_5 lattice.at n=29A005930
- Theta series of A_5 lattice.at n=38A008445
- Binomial transform of Thue-Morse sequence A010060.at n=14A019302
- Theta series of A*_11 lattice.at n=60A023923
- Theta series of 8-d 6-modular lattice G_2 tensor F_4 (or A_2 tensor D_4) with det 1296 and minimal norm 4 in powers of q^2.at n=10A028977
- Shortest edge c of (measured by the longest edge) primitive Euler bricks (a, b, c, sqrt(a^2 + b^2), sqrt(b^2 + c^2), sqrt(a^2 + c^2) are integers).at n=34A031175
- 8 times triangular numbers: a(n) = 4*n*(n+1).at n=44A033996
- For all n, if d is recursively applied to a(n) exactly 6 times then the fixed point of d-iteration is just reached.at n=1A036458
- Numbers having four 0's in base 6.at n=18A043372
- Number of nonnegative solutions of x1^2 + x2^2 + ... + x10^2 = n.at n=15A045852
- Denominator of Sum_{k=1..n} 1/phi(k).at n=23A048049
- Denominator of Sum_{k=1..n} 1/phi(k).at n=22A048049
- a(n) = (n+7)!/7!.at n=4A049388
- Generalized Stirling number triangle of first kind.at n=10A051379
- a(n) = lcm{ phi(1), ..., phi(n) }, where phi is Euler's totient function A000010.at n=22A051547