199911997 has 2 divisors, whose sum is σ = 199911998. Its totient is φ = 199911996.

The previous prime is 199911989. The next prime is 199912081. The reversal of 199911997 is 799119991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 199911321 + 676 = 14139^2 + 26^2 .

It is a cyclic number.

It is not a de Polignac number, because 199911997 - 2³ = 199911989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199911937) 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, 99955998 + 99955999.

It is an arithmetic number, because the mean of its divisors is an integer number (99955999).

Almost surely, 2^199911997 is an apocalyptic number.

It is an amenable number.

199911997 is a deficient number, since it is larger than the sum of its proper divisors (1).

199911997 is an equidigital number, since it uses as much as digits as its factorization.

199911997 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 413343, while the sum is 55.

The square root of 199911997 is about 14139.0239054894. The cubic root of 199911997 is about 584.7177609479.

The spelling of 199911997 in words is "one hundred ninety-nine million, nine hundred eleven thousand, nine hundred ninety-seven".