155 (number) explained

Number:	155
Divisor:	1, 5, 31, 155

155 (one hundred [and] fifty-five) is the natural number following 154 and preceding 156.

In mathematics

155 is:

• a composite number
• a semiprime.
• a deficient number, since 1+5+31=37<155.

10011011 _{2} has a total of 5 ones in it.

There are 155 primitive permutation groups of degree 81.

If one adds up all the primes from the least through the greatest prime factors of 155, that is, 5 and 31, the result is 155. Only three other "small" semiprimes (10, 39, and 371) share this attribute.