198764021 has 2 divisors, whose sum is σ = 198764022. Its totient is φ = 198764020.

The previous prime is 198764011. The next prime is 198764053. The reversal of 198764021 is 120467891.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 193071025 + 5692996 = 13895^2 + 2386^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-198764021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (198764011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 99382010 + 99382011.

It is an arithmetic number, because the mean of its divisors is an integer number (99382011).

Almost surely, 2^198764021 is an apocalyptic number.

It is an amenable number.

198764021 is a deficient number, since it is larger than the sum of its proper divisors (1).

198764021 is an equidigital number, since it uses as much as digits as its factorization.

198764021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 24192, while the sum is 38.

The square root of 198764021 is about 14098.3694447266. The cubic root of 198764021 is about 583.5963826593.

The spelling of 198764021 in words is "one hundred ninety-eight million, seven hundred sixty-four thousand, twenty-one".