491866859 has 4 divisors (see below), whose sum is σ = 536582040. Its totient is φ = 447151680.

The previous prime is 491866849. The next prime is 491866861. The reversal of 491866859 is 958668194.

It is a happy number.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-491866859 is a prime.

It is a super-3 number, since 3×491866859³ (a number of 27 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (491866819) 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, 22357574 + ... + 22357595.

It is an arithmetic number, because the mean of its divisors is an integer number (134145510).

Almost surely, 2^491866859 is an apocalyptic number.

491866859 is a deficient number, since it is larger than the sum of its proper divisors (44715181).

491866859 is a wasteful number, since it uses less digits than its factorization.

491866859 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 44715180.

The product of its digits is 3732480, while the sum is 56.

The square root of 491866859 is about 22178.0715798286. The cubic root of 491866859 is about 789.3734598603.

The spelling of 491866859 in words is "four hundred ninety-one million, eight hundred sixty-six thousand, eight hundred fifty-nine".