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991000 = 2353991
BaseRepresentation
bin11110001111100011000
31212100101201
43301330120
5223203000
633123544
711265133
oct3617430
91770351
10991000
1161760a
123b95b4
132890ba
141bb21a
1514896a
hexf1f18

991000 has 32 divisors (see below), whose sum is σ = 2321280. Its totient is φ = 396000.

The previous prime is 990989. The next prime is 991009. The reversal of 991000 is 199.

It is a nialpdrome in base 10.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991009) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 505 + ... + 1495.

It is an arithmetic number, because the mean of its divisors is an integer number (72540).

2991000 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 991000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1160640).

991000 is an abundant number, since it is smaller than the sum of its proper divisors (1330280).

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

991000 is a wasteful number, since it uses less digits than its factorization.

991000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1012 (or 998 counting only the distinct ones).

The product of its (nonzero) digits is 81, while the sum is 19.

The square root of 991000 is about 995.4898291796. The cubic root of 991000 is about 99.6990954728.

Adding to 991000 its reverse (199), we get a palindrome (991199).

The spelling of 991000 in words is "nine hundred ninety-one thousand".

Divisors: 1 2 4 5 8 10 20 25 40 50 100 125 200 250 500 991 1000 1982 3964 4955 7928 9910 19820 24775 39640 49550 99100 123875 198200 247750 495500 991000