199745321 has 2 divisors, whose sum is σ = 199745322. Its totient is φ = 199745320.

The previous prime is 199745311. The next prime is 199745323. The reversal of 199745321 is 123547991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 154654096 + 45091225 = 12436^2 + 6715^2 .

It is a cyclic number.

It is not a de Polignac number, because 199745321 - 2¹⁰ = 199744297 is a prime.

It is a super-2 number, since 2×199745321² = 79796386522786082, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 199745323, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (199745323) 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 as a sum of consecutive naturals, namely, 99872660 + 99872661.

It is an arithmetic number, because the mean of its divisors is an integer number (99872661).

Almost surely, 2^199745321 is an apocalyptic number.

It is an amenable number.

199745321 is a deficient number, since it is larger than the sum of its proper divisors (1).

199745321 is an equidigital number, since it uses as much as digits as its factorization.

199745321 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 68040, while the sum is 41.

The square root of 199745321 is about 14133.1284930124. The cubic root of 199745321 is about 584.5552135658. Note that the first 3 decimals are identical.

The spelling of 199745321 in words is "one hundred ninety-nine million, seven hundred forty-five thousand, three hundred twenty-one".