491891568 has 80 divisors (see below), whose sum is σ = 1456573440. Its totient is φ = 140122368.

The previous prime is 491891563. The next prime is 491891611. The reversal of 491891568 is 865198194.

It is a self number, because there is not a number n which added to its sum of digits gives 491891568.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (491891563) 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, 121318 + ... + 125306.

It is an arithmetic number, because the mean of its divisors is an integer number (18207168).

Almost surely, 2^491891568 is an apocalyptic number.

491891568 is a gapful number since it is divisible by the number (48) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 491891568, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (728286720).

491891568 is an abundant number, since it is smaller than the sum of its proper divisors (964681872).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

491891568 is a wasteful number, since it uses less digits than its factorization.

491891568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4374 (or 4368 counting only the distinct ones).

The product of its digits is 622080, while the sum is 51.

The square root of 491891568 is about 22178.6286320863. The cubic root of 491891568 is about 789.3866777341.

The spelling of 491891568 in words is "four hundred ninety-one million, eight hundred ninety-one thousand, five hundred sixty-eight".