991879736646400 has 864 divisors, whose sum is σ = 2965060368990720. Its totient is φ = 320910999552000.

The previous prime is 991879736646397. The next prime is 991879736646439. The reversal of 991879736646400 is 4646637978199.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 253224337242 + ... + 253224341158.

It is an arithmetic number, because the mean of its divisors is an integer number (3431782834480).

Almost surely, 2^{991879736646400} 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 991879736646400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1482530184495360).

991879736646400 is an abundant number, since it is smaller than the sum of its proper divisors (1973180632344320).

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

991879736646400 is a wasteful number, since it uses less digits than its factorization.

991879736646400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5061 (or 5042 counting only the distinct ones).

The product of its (nonzero) digits is 2962842624, while the sum is 79.

The spelling of 991879736646400 in words is "nine hundred ninety-one trillion, eight hundred seventy-nine billion, seven hundred thirty-six million, six hundred forty-six thousand, four hundred".