199981109 has 2 divisors, whose sum is σ = 199981110. Its totient is φ = 199981108.

The previous prime is 199981097. The next prime is 199981121. The reversal of 199981109 is 901189991.

It is a happy number.

It is a balanced prime because it is at equal distance from previous prime (199981097) and next prime (199981121).

It can be written as a sum of positive squares in only one way, i.e., 143400625 + 56580484 = 11975^2 + 7522^2 .

It is a cyclic number.

It is not a de Polignac number, because 199981109 - 2⁸ = 199980853 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199981139) 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, 99990554 + 99990555.

It is an arithmetic number, because the mean of its divisors is an integer number (99990555).

Almost surely, 2^199981109 is an apocalyptic number.

It is an amenable number.

199981109 is a deficient number, since it is larger than the sum of its proper divisors (1).

199981109 is an equidigital number, since it uses as much as digits as its factorization.

199981109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 52488, while the sum is 47.

The square root of 199981109 is about 14141.4677102485. The cubic root of 199981109 is about 584.7851345231.

The spelling of 199981109 in words is "one hundred ninety-nine million, nine hundred eighty-one thousand, one hundred nine".