491116821 has 16 divisors (see below), whose sum is σ = 706038144. Its totient is φ = 301863744.

The previous prime is 491116817. The next prime is 491116823. The reversal of 491116821 is 128611194.

It is not a de Polignac number, because 491116821 - 2² = 491116817 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (491116823) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27495 + ... + 41691.

It is an arithmetic number, because the mean of its divisors is an integer number (44127384).

Almost surely, 2^491116821 is an apocalyptic number.

It is an amenable number.

491116821 is a deficient number, since it is larger than the sum of its proper divisors (214921323).

491116821 is a wasteful number, since it uses less digits than its factorization.

491116821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15100.

The product of its digits is 3456, while the sum is 33.

The square root of 491116821 is about 22161.1556783485. The cubic root of 491116821 is about 788.9720224417.

The spelling of 491116821 in words is "four hundred ninety-one million, one hundred sixteen thousand, eight hundred twenty-one".