1619

This number is a prime.

+ A prime whose cube can be expressed as the sum of three prime squares in two different ways, i.e., 16193 is 32 + 249672 + 601692 and 32 + 281632 + 587412. [Rivera]

+ Kepler's 3rd Law of planetary motion wasn't published until 1619.

+ The smallest nonprime-digit emirp that remains a nonprime-digit emirp when each digit is replaced by its complement (9491). Note that it is also the smallest nonprime-digit emirp that remains an emirp when sandwiched between a pair of prime digits (316193) and that the sum of digits is prime in all cases. [Beedassy]

+ Exactly half of the first 3238 positive integers (1619) contain no twos. [Gaydos]

+ 1619 is the 256th prime. If you square the number formed from the first two digits in ascending order, namely 16, you get 256. [Missailidis]

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