199609193857 has 2 divisors, whose sum is σ = 199609193858. Its totient is φ = 199609193856.

The previous prime is 199609193813. The next prime is 199609193867. The reversal of 199609193857 is 758391906991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 173235758656 + 26373435201 = 416216^2 + 162399^2 .

It is an emirp because it is prime and its reverse (758391906991) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-199609193857 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 199609193792 and 199609193801.

It is not a weakly prime, because it can be changed into another prime (199609193867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99804596928 + 99804596929.

It is an arithmetic number, because the mean of its divisors is an integer number (99804596929).

Almost surely, 2^199609193857 is an apocalyptic number.

It is an amenable number.

199609193857 is a deficient number, since it is larger than the sum of its proper divisors (1).

199609193857 is an equidigital number, since it uses as much as digits as its factorization.

199609193857 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 33067440, while the sum is 67.

The spelling of 199609193857 in words is "one hundred ninety-nine billion, six hundred nine million, one hundred ninety-three thousand, eight hundred fifty-seven".