198561963661 has 2 divisors, whose sum is σ = 198561963662. Its totient is φ = 198561963660.

The previous prime is 198561963629. The next prime is 198561963667. The reversal of 198561963661 is 166369165891.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 144081735561 + 54480228100 = 379581^2 + 233410^2 .

It is a cyclic number.

It is not a de Polignac number, because 198561963661 - 2⁵ = 198561963629 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 198561963661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (198561963667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99280981830 + 99280981831.

It is an arithmetic number, because the mean of its divisors is an integer number (99280981831).

Almost surely, 2^198561963661 is an apocalyptic number.

It is an amenable number.

198561963661 is a deficient number, since it is larger than the sum of its proper divisors (1).

198561963661 is an equidigital number, since it uses as much as digits as its factorization.

198561963661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12597120, while the sum is 61.

The spelling of 198561963661 in words is "one hundred ninety-eight billion, five hundred sixty-one million, nine hundred sixty-three thousand, six hundred sixty-one".