What is 61 numbers?

61 is a prime number. It is the 18th prime number and the smallest prime number that is the sum of two distinct prime numbers (31 + 29). In Roman numerals, 61 is written as LXI. It is also the atomic number of the element promethium. In mathematics, 61 is a unique prime because it is the smallest prime that appears in a three-term arithmetic progression of primes, namely, 61, 67, 73. It is also a part of the Fibonacci sequence. In technology, 61 is the country code for international direct dial phone calls to Australia.