145 (number)

145 (one hundred forty-five) is a whole number. It comes after 144 and before 146.

In mathematics

• Composite number: 145 is a composite number. It can be factored into 5×29. Both 5 and 29 are prime numbers, so 145 is also called a semiprime.
• Factorion: 145 is special because it is the sum of the factorials of its digits:1!+4!+5!=1+24+120=145.A number like this is called a factorion.
• 10th pentagonal number: 145 is the 10th pentagonal number. This means 210×(3×10−1)=145.
• Not a Harshad number: The sum of its digits is 1+4+5=10. Since 145÷10=14.5 is not an integer, 145 is not a Harshad number.
• In different bases:
  • In binary (base 2), 145 is written as 10010001.
  • In octal (base 8), 145 is written as 221.
  • In hexadecimal (base 16), 145 is written as 91.