128
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 11
- Digital Root
- 2
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 255
- Proper Divisor Sum (Aliquot Sum)
- 127
- 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
- 64
- Möbius Function
- 0
- Radical
- 2
- Omega Function (Ω)
- 7
- Little Omega Function (ω)
- 1
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
- 7
- Smith Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- Squarefree Number
- no
- Prime Power
- yes
- Prime Factorization
- no
- Twin Prime
- no
- Mersenne Prime
- no
- Sophie Germain Prime
- no
- Safe Prime
- no
- Powerful Number
- yes
- Achilles Number
- no
- Perfect Power
- yes
- Smooth Number
- yes
- Carmichael Number
- no
Classification
- Even
- yes
- Odd
- no
Names
- German
- einshundertachtundzwanzig· ordinal: einshundertachtundzwanzigste
- English
- one hundred twenty-eight· ordinal: one hundred twenty-eighth
- Spanish
- ciento veintiocho· ordinal: 128º
- French
- cent vingt-huit· ordinal: cent vingt-huitième
- Italian
- centoventotto· ordinal: 128º
- Latin
- centum viginti octo· ordinal: 128.
- Portuguese
- cento e vinte e oito· ordinal: 128º
Appears in sequences
- Let k = p_1^e_1 p_2^e_2 p_3^e_3 ... be the prime factorization of n. Sequence gives k such that the sum of the numbers of 1's in the binary expansions of e_1, e_2, e_3, ... is odd.at n=60A000028
- Generalized tangent numbers d(n,1).at n=47A000061
- Odious numbers: numbers with an odd number of 1's in their binary expansion.at n=64A000069
- Positive zeros of Bessel function of order 0 rounded to nearest integer.at n=40A000134
- Generalized tangent numbers d_(n,2).at n=3A000176
- Generalized tangent numbers d(4,n).at n=1A000318
- One-half the number of permutations of length n with exactly 2 rising or falling successions.at n=6A000349
- Numbers that are the sum of 2 nonzero squares.at n=44A000404
- Numbers that are the sum of 2 but no fewer nonzero squares.at n=42A000415
- Numbers that are not the sum of 4 nonzero squares.at n=17A000534
- Numbers that are the sum of 2 squares but not sum of 3 nonzero squares.at n=19A000549
- Number of trees of diameter 7.at n=4A000550
- Total number of 1's in binary expansions of 0, ..., n.at n=47A000788
- Numbers beginning with a vowel in English.at n=42A000852
- Numbers beginning with letter 'o' in English.at n=29A000865
- Number of twin prime pairs < square of n-th prime.at n=19A000885
- Conjecturally largest even integer which is an unordered sum of two primes in exactly n ways.at n=3A000954
- Powers of primes. Alternatively, 1 and the prime powers (p^k, p prime, k >= 1).at n=44A000961
- a(n) = ceiling(n^2/2).at n=16A000982
- Jordan-Polya numbers: products of factorial numbers A000142.at n=15A001013