1645
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 16
- Digital Root
- 7
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 8
- Divisor Sum
- 2304
- Proper Divisor Sum (Aliquot Sum)
- 659
- 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
- 1104
- Möbius Function
- -1
- Radical
- 1645
- 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
- 135
- 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
- Number of partitions of floor(5n/2)-1 into n nonnegative integers each no more than 5.at n=21A001976
- Numbers k such that the k-th tetrahedral number is the sum of 2 tetrahedral numbers.at n=41A002311
- Expansion of chi(x)^10 / phi(x)^4 in powers of x where phi(), chi() are Ramanujan theta functions.at n=12A002512
- "Magic" integers: a(n+1) is the smallest integer m such that there is no overlap between the sets {m, m-a(i), m+a(i): 1 <= i <= n} and {a(i), a(i)-a(j), a(i)+a(j): 1 <= j < i <= n}.at n=25A004210
- a(n) = ceiling(n*phi^8), where phi is the golden ratio, A001622.at n=35A004963
- Spiral sieve using Fibonacci numbers.at n=15A005625
- a(n) = 1 + F(2*n+1) + (-1)^n*L(n).at n=8A006172
- Coordination sequence T6 for Zeolite Code BOG.at n=29A008054
- Coordination sequence T4 for Zeolite Code -PAR.at n=29A009858
- Super-3 Numbers (3n^3 contains substring '333' in its decimal expansion).at n=9A014569
- Pseudoprimes to base 46.at n=23A020174
- Pseudoprimes to base 48.at n=13A020176
- Pseudoprimes to base 93.at n=19A020221
- Numbers k such that the continued fraction for sqrt(k) has period 26.at n=35A020365
- Positive numbers k such that k and 3*k are anagrams in base 9 (written in base 9).at n=16A023080
- Integer part of ((4th elementary symmetric function of 1,2,..,n)/(2nd elementary symmetric function of 1,2,...,n)).at n=16A024173
- s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n+1-k), where k = [ (n+1)/2 ], s = A023532, t = (odd natural numbers).at n=52A024372
- s(1)t(n) + s(2)t(n-1) + ... + s(k)t(n-k+1), where k = [ n/2 ], s = A023532, t = (odd natural numbers).at n=51A025072
- Number of partitions of n into distinct parts >= 4.at n=59A025149
- Expansion of 1/((1-2x)(1-4x)(1-5x)(1-6x)).at n=3A025958