7626
domain: N
Properties
Digital Properties
- Digit Count
- 4
- Digit Sum
- 21
- Digital Root
- 3
- Palindromic Number
- no
- Repdigit
- no
- Automorphic
- no
- Kaprekar Number
- no
- Multiplicative Persistence
- 2
Divisibility
- Divisor Count
- 16
- Divisor Sum
- 16128
- Proper Divisor Sum (Aliquot Sum)
- 8502
- Abundant Number
- yes
- Perfect Number
- no
- Deficient Number
- no
- Highly Composite
- no
- Weird Number
- no
- Untouchable Number
- no
- Primitive Abundant
- no
Derived Values
- Euler's Totient
- 2400
- Möbius Function
- 1
- Radical
- 7626
- Omega Function (Ω)
- 4
- Little Omega Function (ω)
- 4
Special
- Factorial
- no
- Catalan Number
- no
- Bell Number
- no
- Motzkin Number
- no
- Primorial
- no
Figurate Numbers
- Fibonacci Number
- no
- Triangular Number
- yes
- Perfect Square
- no
- Perfect Cube
- no
- Pentagonal Number
- no
- Hexagonal Number
- yes
- 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
- 31
- 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
- yes
- Odd
- no
Appears in sequences
- a(n) = 2*n*(4*n - 1).at n=31A014635
- Positive numbers having the same set of digits in base 7 and base 9.at n=33A037439
- Iterated procedure 'composite k added to sum of its prime factors reaches a prime' yields 9 skipped primes.at n=40A050776
- Write the numbers from 1 to n^2 in a spiraling square; a(n) is the total of the sums of the two diagonals.at n=18A059924
- Numbers k such that phi(k) + 1 = x^2 and sigma(k) + 1 = y^2 for some x and y.at n=38A063532
- Triangular numbers with sum of digits = 21.at n=8A068131
- Binomial(sigma(n),omega(n)), where sigma(n) is the sum of divisors of n (A000203) and omega the number of distinct prime factors (A001221).at n=47A068905
- a(1) = 1; a(2) = 1; a(n) = prime(a(n-1)) + prime(a(n-2)) if n > 2.at n=7A069103
- Triangular numbers of the form 6*k.at n=41A069497
- The smallest magic constant for n X n magic square with prime entries (regarding 1 as a prime).at n=11A073502
- Triangular numbers which are 4-almost primes.at n=33A076578
- Positive integers not expressible as the sum of a prime and a triangular number.at n=49A076768
- a(1) = 1, a(n+1)= smallest triangular number greater than the n-th partial sum.at n=12A076971
- a(n) = triangular number whose index is the concatenation of the first n natural numbers.at n=2A077694
- a(n) = (25*n^2 - 15*n + 2)/2.at n=25A080857
- Staggered diagonal of triangular spiral in A051682.at n=41A081266
- Triangular numbers whose digit reversal is a semiprime (A001358).at n=37A115742
- Number of permutations of length n which avoid the patterns 2143, 2341, 3214.at n=8A116779
- Triangular numbers for which the sum of the digits is an octagonal number.at n=11A117523
- Hexagonal numbers divisible by 6.at n=21A117794