198778165 has 4 divisors (see below), whose sum is σ = 238533804. Its totient is φ = 159022528.

The previous prime is 198778109. The next prime is 198778219. The reversal of 198778165 is 561877891.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 102070609 + 96707556 = 10103^2 + 9834^2 .

It is a cyclic number.

It is not a de Polignac number, because 198778165 - 2¹⁷ = 198647093 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19877812 + ... + 19877821.

It is an arithmetic number, because the mean of its divisors is an integer number (59633451).

Almost surely, 2^198778165 is an apocalyptic number.

It is an amenable number.

198778165 is a deficient number, since it is larger than the sum of its proper divisors (39755639).

198778165 is an equidigital number, since it uses as much as digits as its factorization.

198778165 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39755638.

The product of its digits is 846720, while the sum is 52.

The square root of 198778165 is about 14098.8710540951. The cubic root of 198778165 is about 583.6102251905.

The spelling of 198778165 in words is "one hundred ninety-eight million, seven hundred seventy-eight thousand, one hundred sixty-five".