648
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 18
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 20
- Divisor Sum
- 1815
- Proper Divisor Sum (Aliquot Sum)
- 1167
- 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
- 216
- Möbius Function
- 0
- Radical
- 6
- Omega Function (Ω)
- 7
- 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
- yes
- Narcissistic Number
- no
- Collatz Steps
- 25
- Smith Number
- yes
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
- yes
- Achilles Number
- yes
- Perfect Power
- no
- Smooth Number
- yes
- Carmichael Number
- no
Classification
- Even
- yes
- Odd
- no
Names
- German
- sechshundertachtundvierzig· ordinal: sechshundertachtundvierzigste
- English
- six hundred forty-eight· ordinal: six hundred forty-eighth
- Spanish
- seiscientos cuarenta y ocho· ordinal: 648º
- French
- six cent quarante-huit· ordinal: six cent quarante-huitième
- Italian
- seicentoquarantotto· ordinal: 648º
- Latin
- sescenti quadraginta octo· ordinal: 648.
- Portuguese
- seiscentos e quarenta e oito· ordinal: 648º
Appears in sequences
- Order of the group SL(2,Z_n).at n=8A000056
- a(n) = n^2*Product_{p|n} (1 + 1/p).at n=17A000082
- a(n) = a(n-1)*a(n-2)*a(n-3) with a(1)=1, a(2)=2 and a(3)=3.at n=5A000308
- a(n) is smallest number > a(n-1) of form a(i)*a(j), i < j < n.at n=22A000423
- Number of nonnegative solutions to x^2 + y^2 + z^2 <= n^2.at n=10A000604
- a(n) = ceiling(n^2/2).at n=36A000982
- Numbers k such that k / (sum of digits of k) is a square.at n=31A001102
- a(n) = 2*n^2.at n=18A001105
- Numbers that are the sum of 4 cubes in more than 1 way.at n=37A001245
- Number of self-avoiding n-step walks on honeycomb lattice.at n=9A001668
- Powerful numbers, definition (1): if a prime p divides n then p^2 must also divide n (also called squareful, square full, square-full or 2-powerful numbers).at n=41A001694
- Prime numbers of measurement.at n=24A002049
- Maximal kissing number of n-dimensional laminated lattice.at n=12A002336
- Smallest number of stones in Tchoukaillon (or Mancala, or Kalahari) solitaire that make use of n-th hole.at n=44A002491
- Number of strongly asymmetric sequences of length n.at n=5A002842
- Beginnings of periodic unitary aliquot sequences.at n=52A003062
- Self numbers divisible by sum of their digits (or, self numbers which are also Harshad numbers).at n=21A003219
- Denominators of coefficients of Green function for cubic lattice.at n=2A003298
- Numbers that are the sum of 9 positive 5th powers.at n=24A003354
- Number of binary vectors with restricted repetitions.at n=8A003440