199881091 has 2 divisors, whose sum is σ = 199881092. Its totient is φ = 199881090.

The previous prime is 199881061. The next prime is 199881113. The reversal of 199881091 is 190188991.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 199881091 - 2¹⁵ = 199848323 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (199881061) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99940545 + 99940546.

It is an arithmetic number, because the mean of its divisors is an integer number (99940546).

Almost surely, 2^199881091 is an apocalyptic number.

199881091 is a deficient number, since it is larger than the sum of its proper divisors (1).

199881091 is an equidigital number, since it uses as much as digits as its factorization.

199881091 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 46656, while the sum is 46.

The square root of 199881091 is about 14137.9309306560. The cubic root of 199881091 is about 584.6876273245.

The spelling of 199881091 in words is "one hundred ninety-nine million, eight hundred eighty-one thousand, ninety-one".