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BaseRepresentation
bin10100000101
31202121
4110011
520120
65541
73514
oct2405
91677
101285
11a69
128b1
1377b
1467b
155aa
hex505

1285 has 4 divisors (see below), whose sum is σ = 1548. Its totient is φ = 1024.

The previous prime is 1283. The next prime is 1289. The reversal of 1285 is 5821.

It is a happy number.

1285 is nontrivially palindromic in base 2, base 4 and base 16.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 961 + 324 = 31^2 + 18^2 .

It is a 5-Lehmer number, since φ(1285) divides (1285-1)5.

It is a cyclic number.

It is not a de Polignac number, because 1285 - 21 = 1283 is a prime.

It is a house number.

It is a Duffinian number.

1285 is an undulating number in base 16.

1285 is a lucky number.

It is a plaindrome in base 9, base 13, base 14 and base 15.

It is a nialpdrome in base 6.

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.

In principle, a polygon with 1285 sides can be constructed with ruler and compass.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 124 + ... + 133.

It is an arithmetic number, because the mean of its divisors is an integer number (387).

1285 is a Friedman number, since it can be written as 5*(2^8+1), using all its digits and the basic arithmetic operations.

21285 is an apocalyptic number.

It is an amenable number.

1285 is a deficient number, since it is larger than the sum of its proper divisors (263).

1285 is an equidigital number, since it uses as much as digits as its factorization.

1285 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 262.

The product of its digits is 80, while the sum is 16.

The square root of 1285 is about 35.8468966579. The cubic root of 1285 is about 10.8717896897.

The spelling of 1285 in words is "one thousand, two hundred eighty-five".

Divisors: 1 5 257 1285