491181356565 has 48 divisors (see below), whose sum is σ = 921301250688. Its totient is φ = 250573663296.

The previous prime is 491181356543. The next prime is 491181356569. The reversal of 491181356565 is 565653181194.

It is a happy number.

491181356565 is a `hidden beast` number, since 4 + 9 + 1 + 1 + 8 + 13 + 565 + 65 = 666.

It is not a de Polignac number, because 491181356565 - 2¹² = 491181352469 is a prime.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (491181356569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 8760414 + ... + 8816303.

It is an arithmetic number, because the mean of its divisors is an integer number (19193776056).

Almost surely, 2^491181356565 is an apocalyptic number.

491181356565 is a gapful number since it is divisible by the number (45) formed by its first and last digit.

It is an amenable number.

491181356565 is a deficient number, since it is larger than the sum of its proper divisors (430119894123).

491181356565 is a wasteful number, since it uses less digits than its factorization.

491181356565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17576760 (or 17576748 counting only the distinct ones).

The product of its digits is 3888000, while the sum is 54.

The spelling of 491181356565 in words is "four hundred ninety-one billion, one hundred eighty-one million, three hundred fifty-six thousand, five hundred sixty-five".