780
domain: N
Properties
Digital Properties
- Digit Count
- 3
- Digit Sum
- 15
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 2352
- Proper Divisor Sum (Aliquot Sum)
- 1572
- 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
- 192
- Möbius Function
- 0
- Radical
- 390
- Omega Function (Ω)
- 5
- 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
- yes
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- yes
- 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
- 121
- Smith 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
Names
- German
- siebenhundertachtzig· ordinal: siebenhundertachtzigste
- English
- seven hundred eighty· ordinal: seven hundred eightieth
- Spanish
- setecientos ochenta· ordinal: 780º
- French
- sept cent quatre-vingts· ordinal: sept cent quatre-vingtsième
- Italian
- settecentoottanta· ordinal: 780º
- Latin
- septingenti octoginta· ordinal: 780.
- Portuguese
- setecentos e oitenta· ordinal: 780º
Appears in sequences
- Hexagonal numbers: a(n) = n*(2*n-1).at n=20A000384
- Related to population of numbers of form x^2 + y^2.at n=11A000694
- Number of compositions of n into 3 ordered relatively prime parts.at n=40A000741
- Number of twin prime pairs < square of n-th prime.at n=51A000885
- Smallest even number that is an unordered sum of two odd primes in exactly n ways.at n=44A001172
- Double-bitters: only even length runs in binary expansion.at n=18A001196
- a(n) = 4*a(n-1) - a(n-2) with a(0) = 0, a(1) = 1.at n=6A001353
- Number of n-step self-avoiding walks on square lattice.at n=6A001411
- Absolute value of Glaisher's beta'(2n+1).at n=23A002291
- Smallest number of stones in Tchoukaillon (or Mancala, or Kalahari) solitaire that make use of n-th hole.at n=48A002491
- a(n) = 4*a(n-2) - a(n-4) for n > 1, a(n) = n for n = 0, 1.at n=12A002530
- The square sieve.at n=49A002960
- Beginnings of periodic unitary aliquot sequences.at n=66A003062
- Degrees of irreducible representations of group L4(3).at n=27A003900
- Degrees of irreducible representations of Suzuki group Suz.at n=3A003902
- Binomial coefficient C(4n,n-8).at n=2A004338
- Binomial coefficient C(5n, n-6).at n=2A004348
- Binomial coefficient C(8n,n-3).at n=2A004384
- a(n) = (2^n/n!)*Product_{k=0..n-1} (4*k + 5).at n=3A004985
- Representation degeneracies for Ramond strings.at n=10A005305