891721077984 has 768 divisors, whose sum is σ = 3050282188800. Its totient is φ = 250880716800.

The previous prime is 891721077977. The next prime is 891721078021. The reversal of 891721077984 is 489770127198.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 747460492 + ... + 747461684.

It is an arithmetic number, because the mean of its divisors is an integer number (3971721600).

Almost surely, 2^891721077984 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 891721077984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1525141094400).

891721077984 is an abundant number, since it is smaller than the sum of its proper divisors (2158561110816).

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

891721077984 is a wasteful number, since it uses less digits than its factorization.

891721077984 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1356 (or 1342 counting only the distinct ones).

The product of its (nonzero) digits is 14224896, while the sum is 63.

The spelling of 891721077984 in words is "eight hundred ninety-one billion, seven hundred twenty-one million, seventy-seven thousand, nine hundred eighty-four".