247 (two hundred
ndforty-seven) is the
natural number
In mathematics, the natural numbers are the numbers 0, 1, 2, 3, and so on, possibly excluding 0. Some start counting with 0, defining the natural numbers as the non-negative integers , while others start with 1, defining them as the positive in ...
following
246
__NOTOC__
Year 246 ( CCXLVI) was a common year starting on Thursday of the Julian calendar, the 246th Year of the Common Era ( CE) and Anno Domini ( AD) designations, the 246th year of the 1st millennium, the 46th year of the 3rd century, and t ...
and preceding
248
__NOTOC__
Year 248 ( CCXLVIII) was a leap year starting on Saturday of the Julian calendar. At the time, it was known as the Year of the Consulship of Philippus and Severus (or, less frequently, year 1001 ''Ab urbe condita''). The denomination ...
.
Additionally, 247 is:
* a
semiprime
In mathematics, a semiprime is a natural number that is the product of exactly two prime numbers. The two primes in the product may equal each other, so the semiprimes include the squares of prime numbers.
Because there are infinitely many prime n ...
.
* a brilliant number (the product of two primes with the same number of digits).
* a
pentagonal number
A pentagonal number is a figurate number that extends the concept of triangular number, triangular and square numbers to the pentagon, but, unlike the first two, the patterns involved in the construction of pentagonal numbers are not rotational ...
.
* palindromic in base 18 (DD
18).
* a
Harshad number
In mathematics, a harshad number (or Niven number) in a given radix, number base is an integer that is divisible by the digit sum, sum of its digits when written in that base. Harshad numbers in base are also known as -harshad (or -Niven) numbers ...
in bases 10, 14, 19, 20, 27, 39, 40, 58, 77, 79, 115, 118, 229 and 235.
* the smallest number which can be expressed as the difference between two integers that contain together all the decimal digits 0–9. i.e. 247 = 50123 - 49876.
References
Integers
{{Num-stub