891671768640 has 420 divisors, whose sum is σ = 3277542665628. Its totient is φ = 230102415360.

The previous prime is 891671768633. The next prime is 891671768693. The reversal of 891671768640 is 46867176198.

It can be written as a sum of positive squares in 2 ways, for example, as 176077587456 + 715594181184 = 419616^2 + 845928^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 24891222 + ... + 24927018.

Almost surely, 2^891671768640 is an apocalyptic number.

891671768640 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 891671768640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1638771332814).

891671768640 is an abundant number, since it is smaller than the sum of its proper divisors (2385870896988).

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

891671768640 is a wasteful number, since it uses less digits than its factorization.

891671768640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35888 (or 35838 counting only the distinct ones).

The product of its (nonzero) digits is 24385536, while the sum is 63.

The spelling of 891671768640 in words is "eight hundred ninety-one billion, six hundred seventy-one million, seven hundred sixty-eight thousand, six hundred forty".