Number of the day: 1158

William Rowan Hamilton was born on this day 213 years ago.

John Venn was born on this day 184 years ago.

Properties of the number 1158:

1158 = 2 × 3 × 193 is a sphenic number and squarefree.
1158 has 3 distinct prime factors, 8 divisors, 7 antidivisors and 384 totatives.
1158 has an emirpimes digit sum 15 in base 10.
1158 has a triangular digit sum 15 in base 10.
Reversing the decimal digits of 1158 results in a semiprime.
1158 is the sum of 2 positive triangular numbers.
1158 = 1² + 14² + 31² is the sum of 3 positive squares.
1158² = 570² + 1008² is the sum of 2 positive squares in 1 way.
1158² is the sum of 3 positive squares.
1158 is a proper divisor of 773² - 1.
1158 is palindromic in (at least) the following bases: -21, and -89.
1158 in base 19 = 33i and consists of only the digits '3' and 'i'.

The number 1158 belongs to the following On-Line Encyclopedia of Integer Sequences (OEIS) sequences (among others):

Sequence numbers and descriptions below are taken from OEIS.
A005899: Number of points on surface of octahedron; also coordination sequence for cubic lattice: a(0) = 1; for n > 0, a(n) = 4n^2 + 2,
A010000: a(0) = 1, a(n) = n^2 + 2 for n>0.
A025327: Numbers that are the sum of 3 nonzero squares in exactly 7 ways.
A026780: Triangular array T read by rows: T(n,0)=T(n,n)=1 for n >= 0; for n >= 2 and 1<=k<=n-1, T(n,k)=T(n-1,k-1)+T(n-2,k-1)+T(n-1,k) if 1<=k<=[ n/2 ], else T(n,k)=T(n-1,k-1)+T(n-1,k).
A051228: Bernoulli number B_{n} has denominator 42.
A059100: a(n) = n^2 + 2.
A096681: Least k such that decimal representation of k*n contains only digits 0 and 2.
A135850: Numbers n such that there are precisely 6 groups of order n.
A279420: Numbers k such that k^2 has an odd number of digits and the middle digit is 0.
A303305: Generalized 17-gonal (or heptadecagonal) numbers: m*(15*m - 13)/2 with m = 0, +1, -1, +2, -2, +3, -3, ...