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21708 = 223467
BaseRepresentation
bin101010011001100
31002210000
411103030
51143313
6244300
7120201
oct52314
932700
1021708
1115345
1210690
139b5b
147ca8
156673
hex54cc

21708 has 30 divisors (see below), whose sum is σ = 57596. Its totient is φ = 7128.

The previous prime is 21701. The next prime is 21713. The reversal of 21708 is 80712.

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

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

It is not an unprimeable number, because it can be changed into a prime (21701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 291 + ... + 357.

221708 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21708, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28798).

21708 is an abundant number, since it is smaller than the sum of its proper divisors (35888).

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

21708 is a wasteful number, since it uses less digits than its factorization.

21708 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83 (or 72 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 18.

The square root of 21708 is about 147.3363498937. The cubic root of 21708 is about 27.8958717444.

It can be divided in two parts, 21 and 708, that added together give a 6-th power (729 = 36).

The spelling of 21708 in words is "twenty-one thousand, seven hundred eight".

Divisors: 1 2 3 4 6 9 12 18 27 36 54 67 81 108 134 162 201 268 324 402 603 804 1206 1809 2412 3618 5427 7236 10854 21708