97 (number)

97 is:

• the 25th prime number (the largest two-digit prime number in base 10), following 89 and preceding 101.
• a Proth prime and a Pierpont prime as it is 3 × 2⁵ + 1.^[1]
• the eleventh member of the Mian–Chowla sequence.^[2]
• a self number in base 10, since there is no integer that added to its own digits, adds up to 97.^[3]
• the smallest odd prime that is not a cluster prime.^[4]
• the highest two-digit number where the sum of its digits is a square.
• the number of primes less than 2⁹.^[5]
• The numbers 97, 907, 9007, 90007 and 900007 are all primes, and they are all happy primes. However, 9000007 (read as nine million seven) is composite and has the factorization 277 × 32491.
• an emirp with 79.
• an isolated prime, since 95 and 99 are not prime.
• ${\displaystyle {\frac {97}{56}}=1.732{\color {red}1428}\ldots }$ is a commonly used approximation of the irrational number √3

97 is:

• The 10-97 police code means "arrived on the scene"
• The decimal unicode number representing the Latin lowercase "a"^[6]