665198091 has 12 divisors (see below), whose sum is σ = 973005280. Its totient is φ = 437851440.

The previous prime is 665198087. The next prime is 665198123. The reversal of 665198091 is 190891566.

665198091 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 665198091 - 2² = 665198087 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665198021) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 467080 + ... + 468501.

Almost surely, 2^665198091 is an apocalyptic number.

665198091 is a deficient number, since it is larger than the sum of its proper divisors (307807189).

665198091 is a wasteful number, since it uses less digits than its factorization.

665198091 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 935666 (or 935663 counting only the distinct ones).

The product of its (nonzero) digits is 116640, while the sum is 45.

The square root of 665198091 is about 25791.4344502201. The cubic root of 665198091 is about 872.9385336364.

The spelling of 665198091 in words is "six hundred sixty-five million, one hundred ninety-eight thousand, ninety-one".