198188681 has 4 divisors (see below), whose sum is σ = 198227664. Its totient is φ = 198149700.

The previous prime is 198188659. The next prime is 198188699. The reversal of 198188681 is 186881891.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 198188681 - 2¹⁰ = 198187657 is a prime.

It is a super-2 number, since 2×198188681² = 78557506553039522, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (198188651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10475 + ... + 22496.

It is an arithmetic number, because the mean of its divisors is an integer number (49556916).

Almost surely, 2^198188681 is an apocalyptic number.

It is an amenable number.

198188681 is a deficient number, since it is larger than the sum of its proper divisors (38983).

198188681 is an equidigital number, since it uses as much as digits as its factorization.

198188681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38982.

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

The square root of 198188681 is about 14077.9501703906. The cubic root of 198188681 is about 583.0327480680.

The spelling of 198188681 in words is "one hundred ninety-eight million, one hundred eighty-eight thousand, six hundred eighty-one".