15123
domain: N
Properties
Digital Properties
- Digit Count
- 5
- Digit Sum
- 12
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 6
- Divisor Sum
- 20452
- Proper Divisor Sum (Aliquot Sum)
- 5329
- Abundant Number
- no
- Perfect Number
- no
- Deficient Number
- yes
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 9940
- Möbius Function
- 0
- Radical
- 213
- Omega Function (Ω)
- 3
- 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
- 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
- no
- Odd
- yes
Appears in sequences
- Values of A038005 ending in 3.at n=15A038013
- Number of planar polyhexes with n cells with at least two holes, all holes having size at least two.at n=16A038141
- Denominators of continued fraction convergents to sqrt(271).at n=10A041509
- 3p^2 where p runs through the primes.at n=19A079705
- Numbers k such that (k+j) mod (2+j) = 1 for j from 0 to 8 and (k+9) mod 11 <> 1.at n=5A096026
- Triangle read by rows: T(n,k) is the number of skew Dyck paths of semilength n and having k hills (i.e., peaks at level 1) (0 <= k <= n).at n=57A128722
- a(n) = (b(n) + b(n+1))/3, where b(n) = A000366(n).at n=5A130168
- Odd numbers k such that A166100((k-1)/2)/k is not an integer.at n=20A166102
- Numbers n such that n^7 is the sum of a positive fifth power and a square: n^7=x^5+y^2, with repetition.at n=34A175556
- Mirror of the triangle A193965.at n=45A193966
- (5*F(n)+3*L(n)-8)/2.at n=17A206417
- E.g.f. (sin(3x) + cos x) / cos(4x).at n=5A225109
- 3*h^2, where h is an odd integer not divisible by 3.at n=23A229852
- Inverse binomial transform of -2 followed by A000032(n+1).at n=20A244213
- a(n) = A266196(A000079(n)); indices of powers of 2 in A266195.at n=34A266186
- Regular triangle T(n,k) of Dellac configurations with boundaries, n>=1 and k>=0.at n=20A343198
- Number of integer partitions of n with reverse-alternating product > 1.at n=39A347449
- Numbers p^2*q, p > q odd primes such that q divides p+1.at n=13A350245
- Numbers k such that (18^k - 1)^2 - 2 is prime.at n=10A364078
- Number of different coefficient values in expansion of Product_{k=1..n} (1+x^(k^2)).at n=45A369786