197818 has 4 divisors (see below), whose sum is σ = 296730. Its totient is φ = 98908.

The previous prime is 197807. The next prime is 197831. The reversal of 197818 is 818791.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 818791 = 569 ⋅1439.

It can be written as a sum of positive squares in only one way, i.e., 131769 + 66049 = 363^2 + 257^2 .

It is a super-2 number, since 2×197818² = 78263922248, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 49453 + ... + 49456.

2¹⁹⁷⁸¹⁸ is an apocalyptic number.

197818 is a deficient number, since it is larger than the sum of its proper divisors (98912).

197818 is an equidigital number, since it uses as much as digits as its factorization.

197818 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98911.

The product of its digits is 4032, while the sum is 34.

The square root of 197818 is about 444.7673549172. The cubic root of 197818 is about 58.2669030624.

The spelling of 197818 in words is "one hundred ninety-seven thousand, eight hundred eighteen".