198216991 has 8 divisors (see below), whose sum is σ = 239859360. Its totient is φ = 159906048.

The previous prime is 198216947. The next prime is 198217009. The reversal of 198216991 is 199612891.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 198216991 - 2¹³ = 198208799 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 (198216091) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 832726 + ... + 832963.

It is an arithmetic number, because the mean of its divisors is an integer number (29982420).

Almost surely, 2^198216991 is an apocalyptic number.

198216991 is a deficient number, since it is larger than the sum of its proper divisors (41642369).

198216991 is a wasteful number, since it uses less digits than its factorization.

198216991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1665713.

The product of its digits is 69984, while the sum is 46.

The square root of 198216991 is about 14078.9556075726. The cubic root of 198216991 is about 583.0605075936.

The spelling of 198216991 in words is "one hundred ninety-eight million, two hundred sixteen thousand, nine hundred ninety-one".