197909 has 2 divisors, whose sum is σ = 197910. Its totient is φ = 197908.

The previous prime is 197893. The next prime is 197921. The reversal of 197909 is 909791.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 136900 + 61009 = 370^2 + 247^2 .

It is an emirp because it is prime and its reverse (909791) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 197909 - 2⁴ = 197893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (197959) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 98954 + 98955.

It is an arithmetic number, because the mean of its divisors is an integer number (98955).

2¹⁹⁷⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

197909 is a deficient number, since it is larger than the sum of its proper divisors (1).

197909 is an equidigital number, since it uses as much as digits as its factorization.

197909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5103, while the sum is 35.

The square root of 197909 is about 444.8696438284. The cubic root of 197909 is about 58.2758363165.

The spelling of 197909 in words is "one hundred ninety-seven thousand, nine hundred nine".