199243991 has 2 divisors, whose sum is σ = 199243992. Its totient is φ = 199243990.

The previous prime is 199243981. The next prime is 199243999. The reversal of 199243991 is 199342991.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-199243991 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199243999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99621995 + 99621996.

It is an arithmetic number, because the mean of its divisors is an integer number (99621996).

Almost surely, 2^199243991 is an apocalyptic number.

199243991 is a deficient number, since it is larger than the sum of its proper divisors (1).

199243991 is an equidigital number, since it uses as much as digits as its factorization.

199243991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 157464, while the sum is 47.

The square root of 199243991 is about 14115.3813621878. The cubic root of 199243991 is about 584.0657559896.

The spelling of 199243991 in words is "one hundred ninety-nine million, two hundred forty-three thousand, nine hundred ninety-one".