198123665 has 4 divisors (see below), whose sum is σ = 237748404. Its totient is φ = 158498928.

The previous prime is 198123647. The next prime is 198123677. The reversal of 198123665 is 566321891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 566321891 = 1051 ⋅538841.

It can be written as a sum of positive squares in 2 ways, for example, as 128300929 + 69822736 = 11327^2 + 8356^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-198123665 is a prime.

It is a super-3 number, since 3×198123665³ (a number of 26 digits) contains 333 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19812362 + ... + 19812371.

It is an arithmetic number, because the mean of its divisors is an integer number (59437101).

Almost surely, 2^198123665 is an apocalyptic number.

It is an amenable number.

198123665 is a deficient number, since it is larger than the sum of its proper divisors (39624739).

198123665 is an equidigital number, since it uses as much as digits as its factorization.

198123665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39624738.

The product of its digits is 77760, while the sum is 41.

The square root of 198123665 is about 14075.6408379867. The cubic root of 198123665 is about 582.9689862649.

The spelling of 198123665 in words is "one hundred ninety-eight million, one hundred twenty-three thousand, six hundred sixty-five".