198536561 has 4 divisors (see below), whose sum is σ = 203902452. Its totient is φ = 193170672.

The previous prime is 198536549. The next prime is 198536579. The reversal of 198536561 is 165635891.

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 169806961 + 28729600 = 13031^2 + 5360^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-198536561 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (198536501) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2682890 + ... + 2682963.

It is an arithmetic number, because the mean of its divisors is an integer number (50975613).

Almost surely, 2^198536561 is an apocalyptic number.

It is an amenable number.

198536561 is a deficient number, since it is larger than the sum of its proper divisors (5365891).

198536561 is an equidigital number, since it uses as much as digits as its factorization.

198536561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5365890.

The product of its digits is 194400, while the sum is 44.

The square root of 198536561 is about 14090.3002452041. The cubic root of 198536561 is about 583.3736805471.

The spelling of 198536561 in words is "one hundred ninety-eight million, five hundred thirty-six thousand, five hundred sixty-one".