199808991 has 16 divisors (see below), whose sum is σ = 304015200. Its totient is φ = 129605184.

The previous prime is 199808969. The next prime is 199809011.

199808991 is nontrivially palindromic in base 10.

It is not a de Polignac number, because 199808991 - 2⁷ = 199808863 is a prime.

199808991 is a modest number, since divided by 8991 gives 1998 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199808951) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 99006 + ... + 101003.

It is an arithmetic number, because the mean of its divisors is an integer number (19000950).

Almost surely, 2^199808991 is an apocalyptic number.

199808991 is a deficient number, since it is larger than the sum of its proper divisors (104206209).

199808991 is a wasteful number, since it uses less digits than its factorization.

199808991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 200055 (or 200049 counting only the distinct ones).

The product of its (nonzero) digits is 419904, while the sum is 54.

The square root of 199808991 is about 14135.3808226026. The cubic root of 199808991 is about 584.6173171091.

It can be divided in two parts, 19980899 and 1, that added together give a square (19980900 = 4470²).

The spelling of 199808991 in words is "one hundred ninety-nine million, eight hundred eight thousand, nine hundred ninety-one".