12378
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 4
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 24768
- Proper Divisor Sum (Aliquot Sum)
- 12390
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- yes
Derived Values
- Euler's Totient
- 4124
- Möbius Function
- -1
- Radical
- 12378
- Omega Function (Ω)
- 3
- Little Omega Function (ω)
- 3
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
- 37
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- no
- 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
- yes
- Odd
- no
Appears in sequences
- Number of ordered 5-tuples of integers from [ 2,n ] with no common factors among triples.at n=19A015657
- Total number of parts which are positive powers of 2 in all partitions of n.at n=28A073119
- Recamán Fibonacci variation: a(1)=1; a(2)=2; for n > 2, a(n) = a(n-1)+a(n-2)-F(n) if that number is positive and not already in the sequence, otherwise a(n) = a(n-1)+a(n-2)+F(n) where F(n) denotes the n-th Fibonacci number.at n=19A079053
- Average of twin-prime pairs for pairs that are expressible as the sum of two triangular numbers.at n=25A117313
- Integers 1 through n written in primorial base, summed as if decimal.at n=33A122613
- Triangle read by rows: T(n,k) = number of graphs on n node with edge chromatic number k (n >= 1, k >= 1).at n=47A123962
- Triangle read by rows: T(n,k) (n>=0, k=0..n) gives number of connected graphs on n nodes with edge chromatic number k.at n=53A126732
- Admirable numbers in the middle of twin primes.at n=31A135502
- Averages of twin prime pairs which can be represented as a sum of three consecutive of such pair averages.at n=18A160917
- Numbers that are divisible by exactly 3 primes (counted with multiplicity) and sandwiched between primes.at n=30A171179
- Numbers k that divide the sum of digits of 21^k.at n=59A175589
- G.f.: A(x) = Sum_{n>=0} x^n * A(x)^A003188(n) where A003188(n) = n XOR floor(n/2).at n=9A192483
- Numbers n such that n is both the average of some twin prime pair p, q (q = p+2) (i.e., n = p+1 = q-1) and is also the arithmetic mean of the four numbers consisting of the two primes before p and the two primes after q.at n=26A256620
- Numbers n such that 6^n + 5^(n+1) is prime.at n=18A274135
- Number of aperiodic compositions of n where every pair of adjacent parts (including the last with the first) is relatively prime.at n=15A328670
- a(0) = 1; thereafter a(n) = 4*n^2 - 3*n + 2.at n=56A386486