991444320 has 384 divisors, whose sum is σ = 3744921600. Its totient is φ = 244187136.

The previous prime is 991444313. The next prime is 991444393. The reversal of 991444320 is 23444199.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 3857632 + ... + 3857888.

It is an arithmetic number, because the mean of its divisors is an integer number (9752400).

Almost surely, 2^991444320 is an apocalyptic number.

991444320 is a gapful number since it is divisible by the number (90) 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 991444320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1872460800).

991444320 is an abundant number, since it is smaller than the sum of its proper divisors (2753477280).

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

991444320 is a wasteful number, since it uses less digits than its factorization.

991444320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 347 (or 333 counting only the distinct ones).

The product of its (nonzero) digits is 31104, while the sum is 36.

The square root of 991444320 is about 31487.2088315240. The cubic root of 991444320 is about 997.1399344904.

The spelling of 991444320 in words is "nine hundred ninety-one million, four hundred forty-four thousand, three hundred twenty".