64891491768 has 288 divisors, whose sum is σ = 198394560000. Its totient is φ = 19821568320.

The previous prime is 64891491733. The next prime is 64891491803. The reversal of 64891491768 is 86719419846.

64891491768 is a `hidden beast` number, since 6 + 4 + 89 + 1 + 491 + 7 + 68 = 666.

It is an interprime number because it is at equal distance from previous prime (64891491733) and next prime (64891491803).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 30914383 + ... + 30916481.

It is an arithmetic number, because the mean of its divisors is an integer number (688870000).

Almost surely, 2^64891491768 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 64891491768, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (99197280000).

64891491768 is an abundant number, since it is smaller than the sum of its proper divisors (133503068232).

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

64891491768 is a wasteful number, since it uses less digits than its factorization.

64891491768 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2179 (or 2154 counting only the distinct ones).

The product of its digits is 20901888, while the sum is 63.

The spelling of 64891491768 in words is "sixty-four billion, eight hundred ninety-one million, four hundred ninety-one thousand, seven hundred sixty-eight".