199691 has 4 divisors (see below), whose sum is σ = 200592. Its totient is φ = 198792.

The previous prime is 199687. The next prime is 199697. The reversal of 199691 is 196991.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 199691 - 2² = 199687 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 146 + ... + 648.

It is an arithmetic number, because the mean of its divisors is an integer number (50148).

2¹⁹⁹⁶⁹¹ is an apocalyptic number.

199691 is a deficient number, since it is larger than the sum of its proper divisors (901).

199691 is an equidigital number, since it uses as much as digits as its factorization.

199691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 900.

The product of its digits is 4374, while the sum is 35.

The square root of 199691 is about 446.8679894555. The cubic root of 199691 is about 58.4502218578.

The spelling of 199691 in words is "one hundred ninety-nine thousand, six hundred ninety-one".