199101991 has 12 divisors (see below), whose sum is σ = 220080952. Its totient is φ = 179982000.

The previous prime is 199101979. The next prime is 199102003.

199101991 is nontrivially palindromic in base 10.

It is an interprime number because it is at equal distance from previous prime (199101979) and next prime (199102003).

It is not a de Polignac number, because 199101991 - 2¹⁵ = 199069223 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199101901) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 17356 + ... + 26446.

Almost surely, 2^199101991 is an apocalyptic number.

199101991 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

199101991 is a deficient number, since it is larger than the sum of its proper divisors (20978961).

199101991 is a wasteful number, since it uses less digits than its factorization.

199101991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9294 (or 9283 counting only the distinct ones).

The product of its (nonzero) digits is 6561, while the sum is 40.

The square root of 199101991 is about 14110.3504917490. The cubic root of 199101991 is about 583.9269696240.

The spelling of 199101991 in words is "one hundred ninety-nine million, one hundred one thousand, nine hundred ninety-one".