491861664 has 144 divisors (see below), whose sum is σ = 1682815680. Its totient is φ = 133125120.

The previous prime is 491861653. The next prime is 491861681. The reversal of 491861664 is 466168194.

It is a tau number, because it is divible by the number of its divisors (144).

It is a nude number because it is divisible by every one of its digits.

It is a zygodrome in base 12.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 31884 + ... + 44724.

It is an arithmetic number, because the mean of its divisors is an integer number (11686220).

Almost surely, 2^491861664 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 491861664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (841407840).

491861664 is an abundant number, since it is smaller than the sum of its proper divisors (1190954016).

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

491861664 is a wasteful number, since it uses less digits than its factorization.

491861664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12883 (or 12872 counting only the distinct ones).

The product of its digits is 248832, while the sum is 45.

The square root of 491861664 is about 22177.9544593274. The cubic root of 491861664 is about 789.3706807820.

The spelling of 491861664 in words is "four hundred ninety-one million, eight hundred sixty-one thousand, six hundred sixty-four".