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21678 = 233613
BaseRepresentation
bin101010010101110
31002201220
411102232
51143203
6244210
7120126
oct52256
932656
1021678
1115318
1210666
139b37
147c86
156653
hex54ae

21678 has 8 divisors (see below), whose sum is σ = 43368. Its totient is φ = 7224.

The previous prime is 21673. The next prime is 21683. The reversal of 21678 is 87612.

It is an interprime number because it is at equal distance from previous prime (21673) and next prime (21683).

It is a sphenic number, since it is the product of 3 distinct primes.

21678 is an admirable number.

It is an alternating number because its digits alternate between even and odd.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21673) 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, 1801 + ... + 1812.

It is an arithmetic number, because the mean of its divisors is an integer number (5421).

221678 is an apocalyptic number.

21678 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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 (21684).

21678 is a wasteful number, since it uses less digits than its factorization.

21678 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3618.

The product of its digits is 672, while the sum is 24.

The square root of 21678 is about 147.2345068250. The cubic root of 21678 is about 27.8830153172.

The spelling of 21678 in words is "twenty-one thousand, six hundred seventy-eight".

Divisors: 1 2 3 6 3613 7226 10839 21678