1405
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 10
- Digital Root
- 1
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 1
Divisibility
- Divisor Count
- 4
- Divisor Sum
- 1692
- Proper Divisor Sum (Aliquot Sum)
- 287
- 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
- 1120
- Möbius Function
- 1
- Radical
- 1405
- Omega Function (Ω)
- 2
- 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
- 83
- Smith Number
- no
- Vampire Number
- no
Primality
- Prime
- no
- Composite Number
- yes
- Semiprime
- yes
- 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) = ceiling(n^2/2).at n=53A000982
- Number of graphs with n nodes and n-3 edges.at n=11A001431
- Centered square numbers: a(n) = 2*n*(n+1)+1. Sums of two consecutive squares. Also, consider all Pythagorean triples (X, Y, Z=Y+1) ordered by increasing Z; then sequence gives Z values.at n=26A001844
- Denominators of continued fraction convergents to sqrt(10).at n=5A005668
- Tricapped prism numbers.at n=9A005920
- From fundamental unit of Z[ (-n)^{1/4} ].at n=23A006829
- a(n) = n OR n^2 (applied to binary expansions).at n=36A007745
- Coordination sequence T3 for Zeolite Code ATS.at n=27A008040
- Coordination sequence T4 for Zeolite Code MFI.at n=24A008167
- Coordination sequence T2 for Zeolite Code MTW.at n=25A008197
- Coordination sequence T1 for Zeolite Code NES.at n=24A008205
- Crystal ball sequence for A_8 lattice.at n=2A008392
- Positive integers n such that 2^n == 2^5 (mod n).at n=47A015925
- First k>n, not a power of n+1 or one of its prime factors, such that k | n^k + 1.at n=47A015975
- Coordination sequence T1 for Zeolite Code CGF.at n=26A019451
- Pseudoprimes to base 53.at n=21A020181
- Strong pseudoprimes to base 53.at n=3A020279
- 5th Fibonacci polynomial evaluated at x = n!.at n=3A020551
- Numbers k such that Fibonacci(k) == 5 (mod k).at n=45A023176
- a(n) = position of n^2 + (n+1)^2 + (n+2)^2 in A000408.at n=22A024802