199779791 has 2 divisors, whose sum is σ = 199779792. Its totient is φ = 199779790.

The previous prime is 199779787. The next prime is 199779859. The reversal of 199779791 is 197977991.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 199779791 - 2² = 199779787 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 199779791.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199779781) 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, 99889895 + 99889896.

It is an arithmetic number, because the mean of its divisors is an integer number (99889896).

Almost surely, 2^199779791 is an apocalyptic number.

199779791 is a deficient number, since it is larger than the sum of its proper divisors (1).

199779791 is an equidigital number, since it uses as much as digits as its factorization.

199779791 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2250423, while the sum is 59.

The square root of 199779791 is about 14134.3479156274. The cubic root of 199779791 is about 584.5888371473.

The spelling of 199779791 in words is "one hundred ninety-nine million, seven hundred seventy-nine thousand, seven hundred ninety-one".