198539580661 has 2 divisors, whose sum is σ = 198539580662. Its totient is φ = 198539580660.

The previous prime is 198539580653. The next prime is 198539580721. The reversal of 198539580661 is 166085935891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 183778545636 + 14761035025 = 428694^2 + 121495^2 .

It is an emirp because it is prime and its reverse (166085935891) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 198539580661 - 2³ = 198539580653 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 198539580661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (198539580061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99269790330 + 99269790331.

It is an arithmetic number, because the mean of its divisors is an integer number (99269790331).

Almost surely, 2^198539580661 is an apocalyptic number.

It is an amenable number.

198539580661 is a deficient number, since it is larger than the sum of its proper divisors (1).

198539580661 is an equidigital number, since it uses as much as digits as its factorization.

198539580661 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13996800, while the sum is 61.

The spelling of 198539580661 in words is "one hundred ninety-eight billion, five hundred thirty-nine million, five hundred eighty thousand, six hundred sixty-one".