15678
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 27
- Digital Root
- 9
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 37128
- Proper Divisor Sum (Aliquot Sum)
- 21450
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 4752
- Möbius Function
- 0
- Radical
- 5226
- 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
- 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
- 84
- 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
- Expansion of Product_{m>=1} (1 - m*q^m)^3.at n=31A022663
- a(1) = 1, a(n) = a(n-1)/n if a(n-1) is divisible by n else a(n) is the concatenation of a(n-1) and n.at n=7A079791
- Main diagonal of symmetric square array A100936.at n=6A100937
- a(n) = prime(prime(prime(A028815(n) - 1) - 1) - 1) - 1.at n=18A141133
- 3 times 9-gonal (or nonagonal) numbers: a(n) = 3*n*(7*n-5)/2.at n=39A152759
- a(n) = n*(n+1)*(5*n + 4)/6.at n=26A162147
- Append three digits, each increasing by one modulo 10 from the last digit of the nonnegative integers. 0 -> 123, 1 -> 1234 2 -> 2345, ... , 9 -> 9012, 10 -> 10123, etc.at n=15A167231
- a(n) = n*(14*n + 13) + 3.at n=33A195029
- Numbers k which use half of the ten digits such that they have at least one factorization k=p*q that uses remaining half of the digits that are not in k.at n=1A195814
- Antidiagonal sums of the convolution array A213844.at n=11A213846
- Numbers n = p * q, where n, p, and q together contain all 10 digits at least once.at n=1A253172
- Values n, where n = p * q, and n, p, and q together contain all 10 digits at least once, and no digit is in more than one of n, p or q.at n=1A253173
- Counterexamples to a conjecture of Ramanujan about congruences related to the partition function.at n=26A340757
- Number of ways to write n as an ordered sum of 6 nonprime numbers.at n=34A341483
- Numbers k which have a factorization k = f1*f2*...*fr where the digits of {k, f1, f2, ..., fr} together give 0,1,...,9 exactly once.at n=10A370970
- Composite numbers with properties that its digits (which may appear with multiplicity) may not appear in any of its factors (wherein the digits may also appear with multiplicity) and the combined digits of the product and the factors must have at least one of each of the ten digits.at n=17A370972
- Numbers k which have a factorization k = f_1*f_2*...*f_r where f_i >= 1 and the digits of {k, f_1, f_2, ..., f_r} together give 0,1,...,9 exactly once.at n=26A372259