491509736640 has 280 divisors, whose sum is σ = 1882879170480. Its totient is φ = 120986929152.

The previous prime is 491509736609. The next prime is 491509736717. The reversal of 491509736640 is 46637905194.

491509736640 is a `hidden beast` number, since 4 + 9 + 1 + 509 + 73 + 6 + 64 + 0 = 666.

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

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 392370 + ... + 1066289.

It is an arithmetic number, because the mean of its divisors is an integer number (6724568466).

Almost surely, 2^491509736640 is an apocalyptic number.

491509736640 is a gapful number since it is divisible by the number (40) formed by its first and last digit.

It is an amenable number.

491509736640 is an abundant number, since it is smaller than the sum of its proper divisors (1391369433840).

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

491509736640 is a wasteful number, since it uses less digits than its factorization.

491509736640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1458701 (or 1458682 counting only the distinct ones).

The product of its (nonzero) digits is 4898880, while the sum is 54.

The spelling of 491509736640 in words is "four hundred ninety-one billion, five hundred nine million, seven hundred thirty-six thousand, six hundred forty".