198213809 has 2 divisors, whose sum is σ = 198213810. Its totient is φ = 198213808.

The previous prime is 198213791. The next prime is 198213887. The reversal of 198213809 is 908312891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 167133184 + 31080625 = 12928^2 + 5575^2 .

It is an emirp because it is prime and its reverse (908312891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 198213809 - 2¹⁶ = 198148273 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (198213709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99106904 + 99106905.

It is an arithmetic number, because the mean of its divisors is an integer number (99106905).

Almost surely, 2^198213809 is an apocalyptic number.

It is an amenable number.

198213809 is a deficient number, since it is larger than the sum of its proper divisors (1).

198213809 is an equidigital number, since it uses as much as digits as its factorization.

198213809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 31104, while the sum is 41.

The square root of 198213809 is about 14078.8426015777. The cubic root of 198213809 is about 583.0573875979.

The spelling of 198213809 in words is "one hundred ninety-eight million, two hundred thirteen thousand, eight hundred nine".