198764639 has 4 divisors (see below), whose sum is σ = 198918024. Its totient is φ = 198611256.

The previous prime is 198764623. The next prime is 198764647. The reversal of 198764639 is 936467891.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 936467891 = 37 ⋅25309943.

It is a cyclic number.

It is not a de Polignac number, because 198764639 - 2⁴ = 198764623 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (198764239) 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 in 3 ways as a sum of consecutive naturals, for example, 74732 + ... + 77345.

It is an arithmetic number, because the mean of its divisors is an integer number (49729506).

Almost surely, 2^198764639 is an apocalyptic number.

198764639 is a deficient number, since it is larger than the sum of its proper divisors (153385).

198764639 is a wasteful number, since it uses less digits than its factorization.

198764639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153384.

The product of its digits is 1959552, while the sum is 53.

The square root of 198764639 is about 14098.3913621377. The cubic root of 198764639 is about 583.5969875008.

The spelling of 198764639 in words is "one hundred ninety-eight million, seven hundred sixty-four thousand, six hundred thirty-nine".