### Properties of the number 7440:

7440 = 2^{4}× 3 × 5 × 31 is the 6497

^{th}composite number and is not squarefree.

7440 has 4 distinct prime factors, 40 divisors, 9 antidivisors and 1920 totatives.

7440 has an emirpimes digit sum 15 in base 10.

7440 has a triangular digit sum 15 in base 10.

7440 is the difference of 2 nonnegative squares in 12 ways.

7440 is the sum of 2 positive triangular numbers.

7440 is the difference of 2 positive pentagonal numbers in 1 way.

7440 = 40

^{2}+ 52

^{2}+ 56

^{2}is the sum of 3 positive squares.

7440

^{2}= 4464

^{2}+ 5952

^{2}is the sum of 2 positive squares in 1 way.

7440

^{2}is the sum of 3 positive squares.

7440 is a divisor of 311

^{2}- 1.

7440 is palindromic in (at least) base 92.

7440 in base 19 = 11bb and consists of only the digits '1' and 'b'.

7440 in base 30 = 880 and consists of only the digits '0' and '8'.

7440 in base 38 = 55U and consists of only the digits '5' and 'U'.

7440 in base 43 = 411 and consists of only the digits '1' and '4'.

### The number 7440 belongs to the following On-Line Encyclopedia of Integer Sequences (OEIS) sequences (among others):

Sequence numbers and descriptions below are taken from OEIS.A002875: Sorting numbers (see Motzkin article for details).

A024365: Areas of right triangles with co-prime integer sides.

A024406: Ordered areas of primitive Pythagorean triangles.

A032563: Numbers n such that A102489(n) is divisible by n.

A035008: Total number of possible knight moves on an (n+2) X (n+2) chessboard, if the knight is placed anywhere.

A054567: a(n) = 4*n^2 - 7*n + 4.

A055112: a(n) = n*(n+1)*(2*n+1).

A055522: Largest area of a Pythagorean triangle with n as length of one of the three sides (in fact as a leg).

A179693: Products of 4 distinct primes (p^4*q*r*s).

A269619: T(n,k)=Number of length-n 0..k arrays with no repeated value differing from the previous repeated value by other than plus two, zero or minus 1.

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