491961217680 has 560 divisors, whose sum is σ = 1851345434880. Its totient is φ = 121149084672.

The previous prime is 491961217621. The next prime is 491961217681. The reversal of 491961217680 is 86712169194.

491961217680 is a `hidden beast` number, since 4 + 9 + 1 + 9 + 612 + 17 + 6 + 8 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is not an unprimeable number, because it can be changed into a prime (491961217681) 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 111 ways as a sum of consecutive naturals, for example, 38893117 + ... + 38905763.

Almost surely, 2^491961217680 is an apocalyptic number.

491961217680 is a gapful number since it is divisible by the number (40) 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 491961217680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (925672717440).

491961217680 is an abundant number, since it is smaller than the sum of its proper divisors (1359384217200).

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

491961217680 is a wasteful number, since it uses less digits than its factorization.

491961217680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12730 (or 12709 counting only the distinct ones).

The product of its (nonzero) digits is 1306368, while the sum is 54.

The spelling of 491961217680 in words is "four hundred ninety-one billion, nine hundred sixty-one million, two hundred seventeen thousand, six hundred eighty".