Number of the day: 1547

Properties of the number 1547:

1547 is a cyclic number.
1547 = 7 × 13 × 17 is a sphenic number and squarefree.
1547 has 3 distinct prime factors, 8 divisors, 11 antidivisors and 1152 totatives.
1547 has an emirp digit sum 17 in base 10.
1547 has sum of divisors equal to 2016 which is a triangular number.
Reversing the decimal digits of 1547 results in a prime.
1547 = 11³ + 6³ is the sum of 2 positive cubes in 1 way.
1547 = 774² - 773² = 114² - 107² = 66² - 53² = 54² - 37² is the difference of 2 nonnegative squares in 4 ways.
1547 is the difference of 2 positive pentagonal numbers in 4 ways.
1547 = 1² + 5² + 39² is the sum of 3 positive squares.
1547² = 728² + 1365² = 147² + 1540² = 980² + 1197² = 595² + 1428² is the sum of 2 positive squares in 4 ways.
1547² is the sum of 3 positive squares.
1547 is a proper divisor of 883² - 1.
1547 is palindromic in (at least) the following bases: 14, 90, and -12.
1547 in base 14 = 7c7 and consists of only the digits '7' and 'c'.

The number 1547 belongs to the following On-Line Encyclopedia of Integer Sequences (OEIS) sequences (among others):

Sequence numbers and descriptions below are taken from OEIS.
A002412: Hexagonal pyramidal numbers, or greengrocer's numbers.
A002623: G.f.: 1/((1-x)^4*(1+x)).
A014377: Number of connected regular graphs of degree 7 with 2n nodes.
A018805: Number of elements in the set {(x,y): 1 <= x,y <= n, gcd(x,y)=1}.
A024670: Numbers that are sums of 2 distinct positive cubes.
A038812: Number of primes less than 1000n.
A050446: Table T(n,m) giving total degree of n-th-order elementary symmetric polynomials in m variables, -1 <= n, 1 <= m, read by upward antidiagonals.
A050447: Table T(n,m) giving total degree of n-th-order elementary symmetric polynomials in m variables, -1 <= n, 1 <= m, transposed and read by upward antidiagonals.
A068934: Triangular array C(n, r) = number of connected r-regular graphs with n nodes, 0 <= r < n.
A134600: Composite numbers such that the square mean of their prime factors is an integer (where the prime factors are taken with multiplicity and the square mean of c and d is sqrt((c^2+d^2)/2)).