199783921 has 2 divisors, whose sum is σ = 199783922. Its totient is φ = 199783920.

The previous prime is 199783889. The next prime is 199783931. The reversal of 199783921 is 129387991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 189447696 + 10336225 = 13764^2 + 3215^2 .

It is an emirp because it is prime and its reverse (129387991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 199783921 - 2⁵ = 199783889 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (199783931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99891960 + 99891961.

It is an arithmetic number, because the mean of its divisors is an integer number (99891961).

Almost surely, 2^199783921 is an apocalyptic number.

It is an amenable number.

199783921 is a deficient number, since it is larger than the sum of its proper divisors (1).

199783921 is an equidigital number, since it uses as much as digits as its factorization.

199783921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 244944, while the sum is 49.

The square root of 199783921 is about 14134.4940128750. The cubic root of 199783921 is about 584.5928654747.

It can be divided in two parts, 199783 and 921, that added together give a square (200704 = 448²).

The spelling of 199783921 in words is "one hundred ninety-nine million, seven hundred eighty-three thousand, nine hundred twenty-one".