398

398 is a natural number that comes after 397 and before 399. It is an even composite number with prime factorization 2 × 199, where 199 is a prime. As a product of two primes, 398 is a semiprime and has exactly four positive divisors: 1, 2, 199, and 398.

In base representations, 398 equals 110001110 in binary, 616 in octal, and 0x18E in hexadecimal. In Roman numerals, it is written as CCCXCVIII. Geographically or culturally, 398 does not correspond to a widely recognized ordinal or year without additional context.

As the 199th even number, 398 = 2 × 199 is divisible by 2 but not by any smaller primes beyond 2 and 199. The sum of its digits is 20, so 398 is not a Harshad number in base 10. The sum of all positive divisors of 398 is 600, and the sum of its proper divisors is 202.

See also: semiprimes, Roman numerals, base conversion.