The Number 1531: Properties and Meanings1531 is a Prime Number.
1531 appears inside its 4th power.
The Year 1531 ADIn the year 1531 AD "Halley's Comet" visited the Earth.
In the year 1531 AD there was an earthquake at Lisbon.
In the year 1531 AD Three Books of Occult Philosophy by Heinrich Cornelius Agrippa was published in Paris.(Esoteric History)