199981819 has 2 divisors, whose sum is σ = 199981820. Its totient is φ = 199981818.

The previous prime is 199981811. The next prime is 199981841. The reversal of 199981819 is 918189991.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 199981819 - 2³ = 199981811 is a prime.

It is a super-2 number, since 2×199981819² = 79985455861097522, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 199981819.

It is not a weakly prime, because it can be changed into another prime (199981811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99990909 + 99990910.

It is an arithmetic number, because the mean of its divisors is an integer number (99990910).

Almost surely, 2^199981819 is an apocalyptic number.

199981819 is a deficient number, since it is larger than the sum of its proper divisors (1).

199981819 is an equidigital number, since it uses as much as digits as its factorization.

199981819 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 419904, while the sum is 55.

The square root of 199981819 is about 14141.4928137025. The cubic root of 199981819 is about 584.7858265834.

The spelling of 199981819 in words is "one hundred ninety-nine million, nine hundred eighty-one thousand, eight hundred nineteen".