Number of the day: 208

Guido Fubini was born on this day 142 years ago.

Properties of the number 208:

208 is the 74^th totient number.
208 = 2⁴ × 13 is the 161^th composite number and is not squarefree.
208 has 2 distinct prime factors, 10 divisors, 5 antidivisors and 96 totatives.
208 has a semiprime digit sum 10 in base 10.
208 has a triangular digit sum 10 in base 10.
208 has sum of divisors equal to 434 which is a sphenic number.
Reversing the decimal digits of 208 results in a semiprime.
208 = 6³ - 2³ is the difference of 2 positive cubes in 1 way.
208 = 53² - 51² = 28² - 24² = 17² - 9² is the difference of 2 nonnegative squares in 3 ways.
208 is the sum of 2 positive triangular numbers.
208 is the difference of 2 positive pentagonal numbers in 1 way.
208 = 8² + 12² is the sum of 2 positive squares in 1 way.
208 is not the sum of 3 positive squares.
208² = 80² + 192² is the sum of 2 positive squares in 1 way.
208² is the sum of 3 positive squares.
208 is a proper divisor of 79² - 1.
208 is palindromic in (at least) the following bases: 15, 25, 51, -7, -23, and -69.
208 in base 5 = 1313 and consists of only the digits '1' and '3'.
208 in base 6 = 544 and consists of only the digits '4' and '5'.

The number 208 belongs to the following On-Line Encyclopedia of Integer Sequences (OEIS) sequences (among others):

Sequence numbers and descriptions below are taken from OEIS.
A001082: Generalized octagonal numbers: k*(3*k-2), k=0, +- 1, +- 2, +-3, ...
A001399: a(n) is the number of partitions of n into at most 3 parts; also partitions of n+3 in which the greatest part is 3; also number of unlabeled multigraphs with 3 nodes and n edges.
A005101: Abundant numbers (sum of divisors of n exceeds 2n).
A005153: Practical numbers: positive integers m such that every k <= sigma(m) is a sum of distinct divisors of m. Also called panarithmic numbers.
A008574: a(0) = 1, thereafter a(n) = 4n.
A008586: Multiples of 4.
A009766: Catalan's triangle T(n,k) (read by rows): each term is the sum of the entries above and to the left, i.e., T(n,k) = Sum_{j=0..k} T(n-1,j).
A024450: Sum of squares of the first n primes.
A139251: First differences of toothpicks numbers A139250.
A270929: Numbers k such that (16*10^k - 31)/3 is prime.