3975
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 24
- Digital Root
- 6
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 3
Divisibility
- Divisor Count
- 12
- Divisor Sum
- 6696
- Proper Divisor Sum (Aliquot Sum)
- 2721
- 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
- 0
- Radical
- 795
- Omega Function (Ω)
- 4
- 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
- 51
- 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
- Harmonic Molien series for Conway group Con.0.at n=38A008924
- Number of products of distinct primes <= p(n) equal to 1 (mod p(n)).at n=18A024405
- a(n) = dot_product(n,n-1,...2,1)*(5,6,...,n,1,2,3,4).at n=20A026060
- Numbers k such that the continued fraction for sqrt(k) has even period and if the last term of the periodic part is deleted the central term is 21.at n=22A031519
- Numbers k such that the least term in the periodic part of the continued fraction for sqrt(k) is 21.at n=2A031699
- Composite numbers whose prime factors contain no digits other than 3 and 5.at n=35A036315
- Denominators of continued fraction convergents to sqrt(941).at n=8A042821
- Composite numbers with four prime factors (not necessarily distinct) whose concatenation yields a palindrome.at n=4A046453
- Numbers m such that there are precisely 3 groups of order m.at n=19A055561
- Write 0,1,2,3,4,... in a triangular spiral; then a(n) is the sequence found by reading the terms along the line from 0 in the direction 0,2,...at n=30A062708
- Partial sums of A001157: Sum_{j=1..n} sigma_2(j).at n=20A064602
- a(n) = A000166(n)*binomial(n,2).at n=6A065088
- Numbers n such that both n^4 + 2 and n^4 - 2 are prime.at n=22A071351
- Numbers n such that the sum of squarefree numbers from the smallest prime factor of n to the largest prime factor of n is a square.at n=42A074253
- Let p and q be two prime numbers, not necessarily consecutive, such that q - p = 2n; then a(n) is the number of partitions of 2n into even numbers so that each partition corresponds to a consecutive prime difference pattern (k-tuple) and p <= A000230(n).at n=36A079023
- Triangle read by rows: T(n,k), n >=1, 0 <= k <= C(n,k), = number of n X n symmetric positive semi-definite matrices with 2's on the main diagonal and 1's and 0's elsewhere and with k 1's above the diagonal.at n=32A083029
- Sum of the first n primes whose indices are primes.at n=22A083186
- Markoff numbers (A002559) multiplied by 3.at n=13A086326
- (Sum of composites among next n numbers)-(sum of primes among next n numbers).at n=22A094338
- a(1)=1, a(2)=2; for n >= 2, a(n+1) = a(n) + sum of prime factors of a(n).at n=22A096461