198818861 has 2 divisors, whose sum is σ = 198818862. Its totient is φ = 198818860.

The previous prime is 198818833. The next prime is 198818887. The reversal of 198818861 is 168818891.

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., 174504100 + 24314761 = 13210^2 + 4931^2 .

It is a cyclic number.

It is not a de Polignac number, because 198818861 - 2¹⁰ = 198817837 is a prime.

It is a Chen prime.

198818861 is a strobogrammatic number because it is the same when read upside-down.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (198818801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99409430 + 99409431.

It is an arithmetic number, because the mean of its divisors is an integer number (99409431).

Almost surely, 2^198818861 is an apocalyptic number.

It is an amenable number.

198818861 is a deficient number, since it is larger than the sum of its proper divisors (1).

198818861 is an equidigital number, since it uses as much as digits as its factorization.

198818861 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 221184, while the sum is 50.

The square root of 198818861 is about 14100.3142163570. The cubic root of 198818861 is about 583.6500501231.

The spelling of 198818861 in words is "one hundred ninety-eight million, eight hundred eighteen thousand, eight hundred sixty-one".