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.
Other facts
- 145 is an odd number if you look at the last digit (5). However, in base 10, any number ending in 5 is divisible by 5.
- Bus routes, highways, or streets in different places may use the number 145.
145 is known mostly for being a factorion and a pentagonal number.
