991999199 has 2 divisors, whose sum is σ = 991999200. Its totient is φ = 991999198.

The previous prime is 991999189. The next prime is 991999219.

991999199 is nontrivially palindromic in base 10.

It is a weak prime.

It is a palprime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-991999199 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991999189) 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, 495999599 + 495999600.

It is an arithmetic number, because the mean of its divisors is an integer number (495999600).

Almost surely, 2^991999199 is an apocalyptic number.

991999199 is a deficient number, since it is larger than the sum of its proper divisors (1).

991999199 is an equidigital number, since it uses as much as digits as its factorization.

991999199 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4782969, while the sum is 65.

The square root of 991999199 is about 31496.0187801570. The cubic root of 991999199 is about 997.3259220141.

The spelling of 991999199 in words is "nine hundred ninety-one million, nine hundred ninety-nine thousand, one hundred ninety-nine".