There are infinite semiprimes and the sum of their reciprocals does not converge.

Brilliant numbers are semiprimes    for which    and    have the same number of digits.

Chen Jingrun has proved that every sufficiently large even number can be written as the sum of either two primes, or a prime and a semiprime.

The first semiprimes are 4, 6, 9, 10, 14, 15, 21, 22, 25, 26, 33, 34, 35, 38, 39, 46, 49, 51, 55, 57, 58, 62, 65 more terms

Pictorial representation of remainders (mod 2, 3, ...,11) frequency. For a table of values and more details click here

A graph displaying how many semiprimes are multiples of the primes p from 2 to 71. In black the ideal line 1/p.