199999819 has 2 divisors, whose sum is σ = 199999820. Its totient is φ = 199999818.

The previous prime is 199999777. The next prime is 199999831. The reversal of 199999819 is 918999991.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 199999819 - 2⁷ = 199999691 is a prime.

It is a super-2 number, since 2×199999819² = 79999855200065522, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (199999889) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99999909 + 99999910.

It is an arithmetic number, because the mean of its divisors is an integer number (99999910).

Almost surely, 2^199999819 is an apocalyptic number.

199999819 is a deficient number, since it is larger than the sum of its proper divisors (1).

199999819 is an equidigital number, since it uses as much as digits as its factorization.

199999819 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4251528, while the sum is 64.

The square root of 199999819 is about 14142.1292244131. The cubic root of 199999819 is about 584.8033712268.

The spelling of 199999819 in words is "one hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred nineteen".