Sixty-one
From Wikipedia, the free encyclopedia.

Sixty-one (61, LXI) is the natural number following sixty and preceding sixty-two. It is the 18th prime number. The previous is fifty-nine, with which it comprises a twin prime. Sixty-one is the sum of two squares, 5² + 6².

Sixty-one is also:

• The atomic number of promethium, a lanthanide.
• The code for international direct dial phone calls to Australia.

The original article can be found at: http://en.wikipedia.org/wiki/Sixty-one.
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