Kilencvenegy

Kilencvenegy is the Hungarian word for the integer 91. It is written as a single compound word in Hungarian, formed from kilencven (ninety) and egy (one). As a number, 91 follows 90 and precedes 92.

In mathematics, 91 is a composite, odd semiprime with prime factorization 7 × 13. It is the 13th triangular number (the sum of the integers from 1 to 13) and also the 7th hexagonal number, giving it significance in figurate number studies. Its divisors are 1, 7, 13, and 91; the sum of proper divisors is 21, so 91 is a deficient number. In binary it is written as 1011011 and in Roman numerals as XCI.

In science and other contexts, 91 is the atomic number of protactinium (Pa), a radioactive actinide element. The numeral also appears in calendrical and historical references (for example, the years AD 91 or 1991). Its uses are primarily numerical and linguistic, denoting quantity, order, or specific identifiers in diverse fields.