199391 has 4 divisors (see below), whose sum is σ = 204072. Its totient is φ = 194712.

The previous prime is 199379. The next prime is 199399. The reversal of 199391 is 193991.

199391 = T₇₄ + T₇₅ + ... + T₁₁₆.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-199391 is a prime.

It is a Duffinian number.

It is a plaindrome in base 9.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (199399) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2276 + ... + 2361.

It is an arithmetic number, because the mean of its divisors is an integer number (51018).

2¹⁹⁹³⁹¹ is an apocalyptic number.

199391 is a deficient number, since it is larger than the sum of its proper divisors (4681).

199391 is an equidigital number, since it uses as much as digits as its factorization.

199391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4680.

The product of its digits is 2187, while the sum is 32.

The square root of 199391 is about 446.5321936882. The cubic root of 199391 is about 58.4209368541.

The spelling of 199391 in words is "one hundred ninety-nine thousand, three hundred ninety-one".