195961788721 has 2 divisors, whose sum is σ = 195961788722. Its totient is φ = 195961788720.

The previous prime is 195961788677. The next prime is 195961788787. The reversal of 195961788721 is 127887169591.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 164482158096 + 31479630625 = 405564^2 + 177425^2 .

It is an emirp because it is prime and its reverse (127887169591) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 195961788721 - 2¹⁵ = 195961755953 is a prime.

It is not a weakly prime, because it can be changed into another prime (195961786721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 97980894360 + 97980894361.

It is an arithmetic number, because the mean of its divisors is an integer number (97980894361).

Almost surely, 2^195961788721 is an apocalyptic number.

It is an amenable number.

195961788721 is a deficient number, since it is larger than the sum of its proper divisors (1).

195961788721 is an equidigital number, since it uses as much as digits as its factorization.

195961788721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15240960, while the sum is 64.

The spelling of 195961788721 in words is "one hundred ninety-five billion, nine hundred sixty-one million, seven hundred eighty-eight thousand, seven hundred twenty-one".