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20980 = 2251049
BaseRepresentation
bin101000111110100
31001210001
411013310
51132410
6241044
7115111
oct50764
931701
1020980
1114843
1210184
13971b
147908
15633a
hex51f4

20980 has 12 divisors (see below), whose sum is σ = 44100. Its totient is φ = 8384.

The previous prime is 20963. The next prime is 20981. The reversal of 20980 is 8902.

It can be divided in two parts, 209 and 80, that added together give a square (289 = 172).

It can be written as a sum of positive squares in 2 ways, for example, as 13924 + 7056 = 118^2 + 84^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20981) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 505 + ... + 544.

It is an arithmetic number, because the mean of its divisors is an integer number (3675).

220980 is an apocalyptic number.

20980 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

20980 is an abundant number, since it is smaller than the sum of its proper divisors (23120).

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 (22050).

20980 is a wasteful number, since it uses less digits than its factorization.

20980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1058 (or 1056 counting only the distinct ones).

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 20980 is about 144.8447444680. The cubic root of 20980 is about 27.5804804924.

The spelling of 20980 in words is "twenty thousand, nine hundred eighty".

Divisors: 1 2 4 5 10 20 1049 2098 4196 5245 10490 20980