2915
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 17
- Digital Root
- 8
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 3888
- Proper Divisor Sum (Aliquot Sum)
- 973
- 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
- 2080
- Möbius Function
- -1
- Radical
- 2915
- 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
- 35
- 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
- no
- Odd
- yes
Appears in sequences
- a(n) = 4*n^2 - 1.at n=27A000466
- Number of primes < prime(n)^2.at n=37A000879
- a(n) = (4*n+1)*(4*n+3).at n=13A001539
- Numbers n such that n! has a square number of digits.at n=42A006488
- Lucas-Carmichael numbers: squarefree composite numbers k such that p | k => p+1 | k+1.at n=3A006972
- Coordination sequence T2 for Zeolite Code CAS.at n=33A008064
- a(n) = Sum_{k=1..n} k*phi(k).at n=23A011755
- Expansion of e.g.f. arctan(log(x+1)/exp(x)).at n=5A013563
- Partial sums of primes, if 1 is regarded as a prime (as it was until quite recently, see A008578).at n=39A014284
- Pseudoprimes to base 54.at n=17A020182
- Numbers with exactly 6 2's in their ternary expansion.at n=14A023704
- a(n) = Sum_{k=1..n} floor((n/k)*floor(n/k)).at n=42A024921
- a(1) = 3; a(n+1) = a(n)-th nonprime, where nonprimes begin at 1.at n=25A025004
- Number of partitions of n into an odd number of parts, the least being 4; also, a(n+4) = number of partitions of n into an even number of parts, each >=4.at n=58A027190
- Numbers k that divide the (left) concatenation of all numbers <= k written in base 23 (most significant digit on left).at n=19A029492
- Denominator of Bernoulli(2n+2) - Bernoulli(2n).at n=25A029763
- Numbers having period-1 7-digitized sequences.at n=15A031201
- Numbers k such that 147*2^k+1 is prime.at n=24A032423
- Numbers whose set of base-7 digits is {1,3}.at n=37A032914
- Least D in the Pellian x^2 - D*y^2 = 1 for which x has least solution n.at n=52A033314