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1280 = 285
BaseRepresentation
bin10100000000
31202102
4110000
520110
65532
73506
oct2400
91672
101280
11a64
128a8
13776
14676
155a5
hex500

1280 has 18 divisors (see below), whose sum is σ = 3066. Its totient is φ = 512.

The previous prime is 1279. The next prime is 1283. The reversal of 1280 is 821.

Adding to 1280 its product of nonzero digits (16), we get a 4-th power (1296 = 64).

1280 is nontrivially palindromic in base 12, base 14 and base 15.

1280 is an esthetic number in base 14, because in such base its adjacent digits differ by 1.

It can be written as a sum of positive squares in only one way, i.e., 1024 + 256 = 32^2 + 16^2 .

1280 is an undulating number in base 12, base 14 and base 15.

It is a nialpdrome in base 4, base 6, base 11, base 13 and base 16.

It is a zygodrome in base 4.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1283) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (2) of ones.

In principle, a polygon with 1280 sides can be constructed with ruler and compass.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 254 + ... + 258.

21280 is an apocalyptic number.

1280 is a gapful number since it is divisible by the number (10) 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 1280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1533).

1280 is an abundant number, since it is smaller than the sum of its proper divisors (1786).

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

1280 is an frugal number, since it uses more digits than its factorization.

1280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21 (or 7 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 11.

The square root of 1280 is about 35.7770876400. Note that the first 3 decimals coincide. The cubic root of 1280 is about 10.8576704664.

The spelling of 1280 in words is "one thousand, two hundred eighty".

Divisors: 1 2 4 5 8 10 16 20 32 40 64 80 128 160 256 320 640 1280