199205999921 has 2 divisors, whose sum is σ = 199205999922. Its totient is φ = 199205999920.

The previous prime is 199205999879. The next prime is 199206000011. The reversal of 199205999921 is 129999502991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 138547728400 + 60658271521 = 372220^2 + 246289^2 .

It is a cyclic number.

It is not a de Polignac number, because 199205999921 - 2¹⁰ = 199205998897 is a prime.

It is not a weakly prime, because it can be changed into another prime (199205999221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99602999960 + 99602999961.

It is an arithmetic number, because the mean of its divisors is an integer number (99602999961).

Almost surely, 2^199205999921 is an apocalyptic number.

It is an amenable number.

199205999921 is a deficient number, since it is larger than the sum of its proper divisors (1).

199205999921 is an equidigital number, since it uses as much as digits as its factorization.

199205999921 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10628820, while the sum is 65.

The spelling of 199205999921 in words is "one hundred ninety-nine billion, two hundred five million, nine hundred ninety-nine thousand, nine hundred twenty-one".