7540
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
- 1
Divisibility
- Divisor Count
- 24
- Divisor Sum
- 17640
- Proper Divisor Sum (Aliquot Sum)
- 10100
- 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
- 2688
- Möbius Function
- 0
- Radical
- 3770
- Omega Function (Ω)
- 5
- 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
- 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
- 132
- 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
- yes
- Odd
- no
Appears in sequences
- a(n) = Sum_{m=1..n} Sum_{k=1..m} prime(k).at n=23A014148
- Numbers k that divide 4^k + 4.at n=12A015889
- Fibonacci sequence beginning 0, 20.at n=14A022354
- Numbers that are the sum of 2 nonzero squares in exactly 4 ways.at n=42A025287
- Numbers whose set of base-12 digits is {1,4}.at n=29A032824
- Numbers whose set of base-12 digits is {3,4}.at n=29A032836
- a(n) in base 12 is a repdigit.at n=37A048336
- Truncated square pyramid numbers: a(n) = Sum_{k = n..2*n-1} k^2.at n=15A050410
- Iterated procedure 'composite k added to sum of its prime factors reaches a prime' yields 9 skipped primes.at n=39A050776
- Total sum of even parts in all partitions of n.at n=20A066966
- Triangle of numbers relating two sequences A073155 and A073156.at n=31A073153
- Expansion of 1/Product_{ n >= 2, n not of the form 2^k-1 } (1 - x^n).at n=51A078657
- Short leg of primitive Pythagorean triangles having legs that add up to a square, sorted on hypotenuse.at n=21A089547
- Numbers m that are the hypotenuse of exactly 13 distinct integer-sided right triangles, i.e., m^2 can be written as a sum of two squares in 13 ways.at n=35A097102
- Largest number k such that the interval [k^2,(k+1)^2] contains not more than n pairs of twin primes.at n=42A099154
- Bisection of A001157: a(n) = sigma_2(2n-1).at n=42A099978
- Expansion of phi(q)^2*psi(q)^4 in powers of q where phi(),psi() are Ramanujan theta functions.at n=42A122854
- a(n) = Sum_{k=0..n-1} C(n-1,k)* [x^(n-k-1)] A(x)^(k+1) for n>0, with a(0)=1.at n=7A125223
- Fixed points of the permutation A125987/A125988.at n=29A126298
- a(n) = Sum_{k=0..floor(n/2)} (n-k)^2.at n=29A129371