199998221 has 2 divisors, whose sum is σ = 199998222.
Its totient is φ = 199998220.
The previous prime is 199998193. The next prime is 199998241. The reversal of 199998221 is 122899991.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 188512900 + 11485321 = 13730^2 + 3389^2
It is an emirp because it is prime and its reverse (122899991) is a distict prime.
It is a cyclic number.
It is not a de Polignac number, because 199998221 - 26 = 199998157 is a prime.
It is a Chen prime.
It is a self number, because there is not a number n which added to its sum of digits gives 199998221.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (199998241) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99999110 + 99999111.
It is an arithmetic number, because the mean of its divisors is an integer number (99999111).
Almost surely, 2199998221 is an apocalyptic number.
It is an amenable number.
199998221 is a deficient number, since it is larger than the sum of its proper divisors (1).
199998221 is an equidigital number, since it uses as much as digits as its factorization.
199998221 is an evil number, because the sum of its binary digits is even.
The product of its digits is 209952, while the sum is 50.
The square root of 199998221 is about 14142.0727264429.
The cubic root of 199998221 is about 584.8018136949.
The spelling of 199998221 in words is "one hundred ninety-nine million, nine hundred ninety-eight thousand, two hundred twenty-one".