197995198021 has 2 divisors, whose sum is σ = 197995198022. Its totient is φ = 197995198020.

The previous prime is 197995198019. The next prime is 197995198057. The reversal of 197995198021 is 120891599791.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 188148605121 + 9846592900 = 433761^2 + 99230^2 .

It is an emirp because it is prime and its reverse (120891599791) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 197995198021 - 2¹ = 197995198019 is a prime.

Together with 197995198019, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (197992198021) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 98997599010 + 98997599011.

It is an arithmetic number, because the mean of its divisors is an integer number (98997599011).

Almost surely, 2^197995198021 is an apocalyptic number.

It is an amenable number.

197995198021 is a deficient number, since it is larger than the sum of its proper divisors (1).

197995198021 is an equidigital number, since it uses as much as digits as its factorization.

197995198021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3674160, while the sum is 61.

The spelling of 197995198021 in words is "one hundred ninety-seven billion, nine hundred ninety-five million, one hundred ninety-eight thousand, twenty-one".