991458720 has 288 divisors, whose sum is σ = 3962649600. Its totient is φ = 220999680.

The previous prime is 991458707. The next prime is 991458731. The reversal of 991458720 is 27854199.

It is a tau number, because it is divible by the number of its divisors (288).

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

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, 412081 + ... + 414479.

It is an arithmetic number, because the mean of its divisors is an integer number (13759200).

Almost surely, 2^991458720 is an apocalyptic number.

991458720 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 991458720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1981324800).

991458720 is an abundant number, since it is smaller than the sum of its proper divisors (2971190880).

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

991458720 is a wasteful number, since it uses less digits than its factorization.

991458720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2468 (or 2457 counting only the distinct ones).

The product of its (nonzero) digits is 181440, while the sum is 45.

The square root of 991458720 is about 31487.4374949757. The cubic root of 991458720 is about 997.1447620419.

The spelling of 991458720 in words is "nine hundred ninety-one million, four hundred fifty-eight thousand, seven hundred twenty".