199794821 has 2 divisors, whose sum is σ = 199794822. Its totient is φ = 199794820.

The previous prime is 199794817. The next prime is 199794851. The reversal of 199794821 is 128497991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 105801796 + 93993025 = 10286^2 + 9695^2 .

It is an emirp because it is prime and its reverse (128497991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 199794821 - 2² = 199794817 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 199794821.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (199794811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99897410 + 99897411.

It is an arithmetic number, because the mean of its divisors is an integer number (99897411).

Almost surely, 2^199794821 is an apocalyptic number.

It is an amenable number.

199794821 is a deficient number, since it is larger than the sum of its proper divisors (1).

199794821 is an equidigital number, since it uses as much as digits as its factorization.

199794821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326592, while the sum is 50.

The square root of 199794821 is about 14134.8795891582. The cubic root of 199794821 is about 584.6034968714.

The spelling of 199794821 in words is "one hundred ninety-nine million, seven hundred ninety-four thousand, eight hundred twenty-one".