491347640 has 64 divisors (see below), whose sum is σ = 1277726400. Its totient is φ = 166560768.

The previous prime is 491347639. The next prime is 491347687. The reversal of 491347640 is 46743194.

It is a junction number, because it is equal to n+sod(n) for n = 491347594 and 491347603.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15062 + ... + 34778.

It is an arithmetic number, because the mean of its divisors is an integer number (19964475).

Almost surely, 2^491347640 is an apocalyptic number.

491347640 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 491347640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (638863200).

491347640 is an abundant number, since it is smaller than the sum of its proper divisors (786378760).

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

491347640 is a wasteful number, since it uses less digits than its factorization.

491347640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19824 (or 19820 counting only the distinct ones).

The product of its (nonzero) digits is 72576, while the sum is 38.

The square root of 491347640 is about 22166.3628049349. The cubic root of 491347640 is about 789.0956055371.

The spelling of 491347640 in words is "four hundred ninety-one million, three hundred forty-seven thousand, six hundred forty".