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. odious, since its binary expansion has a total of 5 ones in it. Its prime factorization is 5*31, and the sum of the prime numbers between 5 and 31, inclusively, is 155.
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.
Other uses
155 is the airline code for DHL Aviation.
References
External links
https://numbermatics.com/n/155/
https://oeis.org/A000019 https://oeis.org/A055233