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28784 = 247257
BaseRepresentation
bin111000001110000
31110111002
413001300
51410114
6341132
7146630
oct70160
943432
1028784
111a698
12147a8
1310142
14a6c0
1587de
hex7070

28784 has 20 divisors (see below), whose sum is σ = 63984. Its totient is φ = 12288.

The previous prime is 28771. The next prime is 28789. The reversal of 28784 is 48782.

Subtracting from 28784 its product of digits (3584), we obtain a triangular number (25200 = T224).

It can be divided in two parts, 2878 and 4, that added together give a palindrome (2882).

28784 = T57 + T58 + ... + T70.

28784 is an esthetic number in base 9, because in such base its adjacent digits differ by 1.

It is a Smith number, since the sum of its digits (29) coincides with the sum of the digits of its prime factors.

It is a nude number because it is divisible by every one of its digits.

28784 is an undulating number in base 16.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28789) 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, 17 + ... + 240.

28784 is a Friedman number, since it can be written as 7*(8^4+8*2), using all its digits and the basic arithmetic operations.

228784 is an apocalyptic number.

It is an amenable number.

28784 is an abundant number, since it is smaller than the sum of its proper divisors (35200).

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 (31992).

28784 is a wasteful number, since it uses less digits than its factorization.

28784 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 272 (or 266 counting only the distinct ones).

The product of its digits is 3584, while the sum is 29.

The square root of 28784 is about 169.6584804836. The cubic root of 28784 is about 30.6466998781.

The spelling of 28784 in words is "twenty-eight thousand, seven hundred eighty-four".

Divisors: 1 2 4 7 8 14 16 28 56 112 257 514 1028 1799 2056 3598 4112 7196 14392 28784