199723991 has 4 divisors (see below), whose sum is σ = 210235800. Its totient is φ = 189212184.

The previous prime is 199723987. The next prime is 199723999. The reversal of 199723991 is 199327991.

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

It is not a de Polignac number, because 199723991 - 2² = 199723987 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 (199723999) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5255876 + ... + 5255913.

It is an arithmetic number, because the mean of its divisors is an integer number (52558950).

Almost surely, 2^199723991 is an apocalyptic number.

199723991 is a deficient number, since it is larger than the sum of its proper divisors (10511809).

199723991 is a wasteful number, since it uses less digits than its factorization.

199723991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10511808.

The product of its digits is 275562, while the sum is 50.

The square root of 199723991 is about 14132.3738628724. The cubic root of 199723991 is about 584.5344053911.

The spelling of 199723991 in words is "one hundred ninety-nine million, seven hundred twenty-three thousand, nine hundred ninety-one".