991766400 has 384 divisors, whose sum is σ = 3551558400. Its totient is φ = 242319360.

The previous prime is 991766387. The next prime is 991766429. The reversal of 991766400 is 4667199.

It is a tau number, because it is divible by the number of its divisors (384).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 9628749 + ... + 9628851.

It is an arithmetic number, because the mean of its divisors is an integer number (9248850).

Almost surely, 2^991766400 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 991766400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1775779200).

991766400 is an abundant number, since it is smaller than the sum of its proper divisors (2559792000).

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

991766400 is a wasteful number, since it uses less digits than its factorization.

991766400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 206 (or 189 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 42.

The square root of 991766400 is about 31492.3228739958. The cubic root of 991766400 is about 997.2478995580.

The spelling of 991766400 in words is "nine hundred ninety-one million, seven hundred sixty-six thousand, four hundred".