725191

This number is a composite.

725191 is the sum of 313702 and 411489. Note that 313702 and 411489 are the least numbers k such that all integers between 10*k and 10*k+9 contain n-digit prime factor(s), when n = 3 and 4, respectively. Curiously, 725191 is the product of a 3-digit prime and a 4-digit prime (443*1637). [Ikemoto]