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1980 = 2232511
BaseRepresentation
bin11110111100
32201100
4132330
530410
613100
75526
oct3674
92640
101980
111540
121190
13b94
14a16
158c0
hex7bc

1980 has 36 divisors (see below), whose sum is σ = 6552. Its totient is φ = 480.

The previous prime is 1979. The next prime is 1987. The reversal of 1980 is 891.

Subtracting from 1980 its reverse (891), we obtain a square (1089 = 332).

It can be divided in two parts, 19 and 80, that added together give a palindrome (99).

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a plaindrome in base 16.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1987) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 175 + ... + 185.

It is an arithmetic number, because the mean of its divisors is an integer number (182).

21980 is an apocalyptic number.

1980 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a pronic number, being equal to 44×45.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3276).

1980 is an abundant number, since it is smaller than the sum of its proper divisors (4572).

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

1980 is a wasteful number, since it uses less digits than its factorization.

1980 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26 (or 21 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 1980 is about 44.4971909226. The cubic root of 1980 is about 12.5570723564.

The spelling of 1980 in words is "one thousand, nine hundred eighty".

Divisors: 1 2 3 4 5 6 9 10 11 12 15 18 20 22 30 33 36 44 45 55 60 66 90 99 110 132 165 180 198 220 330 396 495 660 990 1980