195557643661 has 2 divisors, whose sum is σ = 195557643662. Its totient is φ = 195557643660.

The previous prime is 195557643629. The next prime is 195557643689. The reversal of 195557643661 is 166346755591.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 103638924900 + 91918718761 = 321930^2 + 303181^2 .

It is an emirp because it is prime and its reverse (166346755591) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 195557643661 - 2⁵ = 195557643629 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 195557643596 and 195557643605.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (195557643691) 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 as a sum of consecutive naturals, namely, 97778821830 + 97778821831.

It is an arithmetic number, because the mean of its divisors is an integer number (97778821831).

Almost surely, 2^195557643661 is an apocalyptic number.

It is an amenable number.

195557643661 is a deficient number, since it is larger than the sum of its proper divisors (1).

195557643661 is an equidigital number, since it uses as much as digits as its factorization.

195557643661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20412000, while the sum is 58.

The spelling of 195557643661 in words is "one hundred ninety-five billion, five hundred fifty-seven million, six hundred forty-three thousand, six hundred sixty-one".