I thought it will be a good idea to spend a little time and understand the number 2015 and it’s properties, because this is way more interesting than doing resolutions for 2015.  So lets start:

2015 – two thousand and fifteen

• it is an odd number;
• its divisors are 1, 5, 13, 31, 65, 155, 403, 2015 (the first 4 divisors are prime; there are 4 divisors divisible by 5) and the sum of its divisors is 2688;
• it is a composite number (not a prime number) with the following decomposition: 2015 = 5 * 13 * 31 (all of them prime numbers), so the square root is not exact;
• looking at its factorization we can see that it is a Lucas-Carmichael number because 2015+1=2016 and 5+1=6, 13+1=14, 31+1=32 are all factors of 2016;
• previous prime is 2011 with a difference of 4 ( 2015 – 2011 = 4) and the next prime is 2017 with a difference of 2 ( 2017 – 2015 = 2 );
• in roman numerals is MMXV;
• in binary notation is 11111011111;
• in hexadecimal notation is 7df;
• considering the year: the 15th year of the 3rd millennium, the 15th year of the 21st century, and the 6th year of the 2010s decade;
• square: 4060225;

For the ones that want to find out more about other properties of 2015 ( more about the properties it doesn’t have, if you ask me) and also if you want to read more about the year 2015, but also I encourage you to read the answers for the question: How can one get 2015 using 1,2,,9 in this order and only once, with the operations +,,×,/(I have found them incredibly interesting).

Also, I encourage you to try the book Numbers: Facts, Figures and Fiction, which tells you a couple of interesting number facts about the number 0 to 156, but if you want to find out more about other big numbers, try NumberADay – Mathematical Association of America’s blog (every working day, they post a number and offer a selection of that number’s properties – quite fun).