491868665840 has 40 divisors (see below), whose sum is σ = 1152324402768. Its totient is φ = 195245573120.

The previous prime is 491868665801. The next prime is 491868665879. The reversal of 491868665840 is 48566868194.

It is an interprime number because it is at equal distance from previous prime (491868665801) and next prime (491868665879).

It is a tau number, because it is divible by the number of its divisors (40).

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 23456537 + ... + 23477496.

Almost surely, 2^491868665840 is an apocalyptic number.

491868665840 is a gapful number since it is divisible by the number (40) formed by its first and last digit.

It is an amenable number.

491868665840 is an abundant number, since it is smaller than the sum of its proper divisors (660455736928).

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

491868665840 is a wasteful number, since it uses less digits than its factorization.

491868665840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46934177 (or 46934171 counting only the distinct ones).

The product of its (nonzero) digits is 79626240, while the sum is 65.

The spelling of 491868665840 in words is "four hundred ninety-one billion, eight hundred sixty-eight million, six hundred sixty-five thousand, eight hundred forty".