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18820 = 225941
BaseRepresentation
bin100100110000100
3221211001
410212010
51100240
6223044
7105604
oct44604
927731
1018820
111315a
12aa84
138749
146c04
15589a
hex4984

18820 has 12 divisors (see below), whose sum is σ = 39564. Its totient is φ = 7520.

The previous prime is 18803. The next prime is 18839. The reversal of 18820 is 2881.

18820 = T33 + T34 + ... + T52.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 9216 + 9604 = 96^2 + 98^2 .

It is a plaindrome in base 15.

It is a nialpdrome in base 12.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 451 + ... + 490.

It is an arithmetic number, because the mean of its divisors is an integer number (3297).

218820 is an apocalyptic number.

18820 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

18820 is an abundant number, since it is smaller than the sum of its proper divisors (20744).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19782).

18820 is a wasteful number, since it uses less digits than its factorization.

18820 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 950 (or 948 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 18820 is about 137.1860051171. The cubic root of 18820 is about 26.5994836616.

It can be divided in two parts, 18 and 820, that added together give a palindrome (838).

The spelling of 18820 in words is "eighteen thousand, eight hundred twenty".

Divisors: 1 2 4 5 10 20 941 1882 3764 4705 9410 18820