197 (number)
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197 is the natural number between 196 and 198. It is also a prime number.
| |||
| Ordinal | One hundred [and] ninety-seven | ||
| Cardinal | 197th | ||
| Factorization | prime number | ||
| Roman numeral | CXCVII | ||
| Binary | 11000101 | ||
| Hexadecimal | C5 | ||
In mathematics
197 is a prime number and a twin prime with 199. The third of a prime quadruplet, 197 sets a record low for the Mertens function, -7. It is also a Chen prime, and an Eisenstein prime with no imaginary part.
There are two different ways of expressing 197 as a sum of consecutive primes: as the sum of the first twelve primes and also the sum of seven consecutive primes (17 + 19 + 23 + 29 + 31 + 37 + 41).
197 is a centered heptagonal number.
197 is a Keith number in base 10, because it recurs in a tribonacci-like sequence started from its digits: 1, 9, 7, 17, 33, 57, 107, 197 ...
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