64891816317891 has 48 divisors (see below), whose sum is σ = 95062756239360. Its totient is φ = 42648982272000.

The previous prime is 64891816317859. The next prime is 64891816317893. The reversal of 64891816317891 is 19871361819846.

64891816317891 is a `hidden beast` number, since 6 + 48 + 9 + 181 + 6 + 317 + 8 + 91 = 666.

It is not a de Polignac number, because 64891816317891 - 2⁵ = 64891816317859 is a prime.

It is a super-2 number, since 2×64891816317891² (a number of 28 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (72) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (64891816317893) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 5695756291 + ... + 5695767683.

It is an arithmetic number, because the mean of its divisors is an integer number (1980474088320).

Almost surely, 2^{64891816317891} is an apocalyptic number.

64891816317891 is a deficient number, since it is larger than the sum of its proper divisors (30170939921469).

64891816317891 is a wasteful number, since it uses less digits than its factorization.

64891816317891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22896 (or 22893 counting only the distinct ones).

The product of its digits is 125411328, while the sum is 72.

The spelling of 64891816317891 in words is "sixty-four trillion, eight hundred ninety-one billion, eight hundred sixteen million, three hundred seventeen thousand, eight hundred ninety-one".