198717891 has 4 divisors (see below), whose sum is σ = 264957192. Its totient is φ = 132478592.

The previous prime is 198717887. The next prime is 198717917.

It is a happy number.

198717891 is nontrivially palindromic in base 10.

198717891 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 198717891 - 2² = 198717887 is a prime.

It is not an unprimeable number, because it can be changed into a prime (198717821) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33119646 + ... + 33119651.

It is an arithmetic number, because the mean of its divisors is an integer number (66239298).

Almost surely, 2^198717891 is an apocalyptic number.

198717891 is a deficient number, since it is larger than the sum of its proper divisors (66239301).

198717891 is an equidigital number, since it uses as much as digits as its factorization.

198717891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66239300.

The product of its digits is 254016, while the sum is 51.

The square root of 198717891 is about 14096.7333449988. The cubic root of 198717891 is about 583.5512313220.

The spelling of 198717891 in words is "one hundred ninety-eight million, seven hundred seventeen thousand, eight hundred ninety-one".