623

623 is a natural number that comes after 622 and before 624. It is a composite number, equal to the product of two distinct primes: 7 and 89. Consequently, its positive divisors are 1, 7, 89, and 623. It is square-free and odd.

In various numeral systems, 623 has the representations: Roman numerals DCXXIII; binary 1001101111; octal 1157; and hexadecimal 0x26F.

As a semiprime, 623 is often cited in elementary discussions of factorization and number theory. Its Euler’s totient function value is φ(623) = (7 − 1)(89 − 1) = 6 × 88 = 528.

In calendar notation, 623 may refer to the year 623 CE (Anno Domini) or 623 BCE, depending on the era being referenced. These years fall in the ancient to early medieval periods, with regional historical significance varying widely and no single event universally identified with the number itself.

Beyond pure mathematics and chronology, the number 623 occasionally appears as an identifier in various catalogs, models, or designations, but these usages are context-dependent and not intrinsic to the number itself.