668558491 has 8 divisors (see below), whose sum is σ = 710715600. Its totient is φ = 627098400.

The previous prime is 668558479. The next prime is 668558521. The reversal of 668558491 is 194855866.

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 668558491 - 2⁵ = 668558459 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (668552491) 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 7 ways as a sum of consecutive naturals, for example, 172276 + ... + 176113.

It is an arithmetic number, because the mean of its divisors is an integer number (88839450).

Almost surely, 2^668558491 is an apocalyptic number.

668558491 is a deficient number, since it is larger than the sum of its proper divisors (42157109).

668558491 is a wasteful number, since it uses less digits than its factorization.

668558491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 348509.

The product of its digits is 2073600, while the sum is 52.

The square root of 668558491 is about 25856.4980420783. The cubic root of 668558491 is about 874.4060147204.

The spelling of 668558491 in words is "six hundred sixty-eight million, five hundred fifty-eight thousand, four hundred ninety-one".