199991321 has 4 divisors (see below), whose sum is σ = 210517200. Its totient is φ = 189465444.

The previous prime is 199991303. The next prime is 199991339. The reversal of 199991321 is 123199991.

199991321 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 123199991 = 97 ⋅1270103.

It is an interprime number because it is at equal distance from previous prime (199991303) and next prime (199991339).

It is a cyclic number.

It is not a de Polignac number, because 199991321 - 2⁶ = 199991257 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (199991381) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5262911 + ... + 5262948.

It is an arithmetic number, because the mean of its divisors is an integer number (52629300).

Almost surely, 2^199991321 is an apocalyptic number.

It is an amenable number.

199991321 is a deficient number, since it is larger than the sum of its proper divisors (10525879).

199991321 is a wasteful number, since it uses less digits than its factorization.

199991321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10525878.

The product of its digits is 39366, while the sum is 44.

The square root of 199991321 is about 14141.8287714143. The cubic root of 199991321 is about 584.7950883369.

The spelling of 199991321 in words is "one hundred ninety-nine million, nine hundred ninety-one thousand, three hundred twenty-one".