249 (two hundred
ndforty-nine) is the
natural number
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country").
Numbers used for counting are called ''Cardinal n ...
following
248
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Year 248 ( CCXLVIII) was a leap year starting on Saturday (link will display the full calendar) 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 '' ...
and preceding
250
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Year 250 ( CCL) was a common year starting on Tuesday (link will display the full calendar) of the Julian calendar. At the time, it was known as the Year of the Consulship of Traianus and Gratus (or, less frequently, year 1003 ''Ab u ...
.
In mathematics
249 is:
*a
Blum integer In mathematics, a natural number ''n'' is a Blum integer if is a semiprime for which ''p'' and ''q'' are distinct prime numbers congruent to 3 mod 4.Joe Hurd, Blum Integers (1997), retrieved 17 Jan, 2011 from http://www.gilith.com/research/talks/ca ...
.
*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 nu ...
.
*palindromic in bases 82 (33
82).
*a
Harshad number
In mathematics, a harshad number (or Niven number) in a given number base is an integer that is divisible by the sum of its digits when written in that base.
Harshad numbers in base are also known as -harshad (or -Niven) numbers.
Harshad numbers ...
in bases 3, 83, 84, 124, 167 and 247.
*the aliquot sum of any of these numbers: 375, 531, 1687, 4351, 7807, 12127, 14647 and 15151.
*part of the 3-aliquot tree. The aliquot sequence starting at 288 is: 288, 531, 249, 87, 33, 15, 9, 4, 3, 1, 0.
References
{{Integers, 2
Integers