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21228 = 2232961
BaseRepresentation
bin101001011101100
31002010020
411023230
51134403
6242140
7115614
oct51354
932106
1021228
1114a49
1210350
13987c
147a44
156453
hex52ec

21228 has 24 divisors (see below), whose sum is σ = 52080. Its totient is φ = 6720.

The previous prime is 21227. The next prime is 21247. The reversal of 21228 is 82212.

21228 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (21221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 318 + ... + 378.

It is an arithmetic number, because the mean of its divisors is an integer number (2170).

221228 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 21228, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26040).

21228 is an abundant number, since it is smaller than the sum of its proper divisors (30852).

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

21228 is a wasteful number, since it uses less digits than its factorization.

21228 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 97 (or 95 counting only the distinct ones).

The product of its digits is 64, while the sum is 15.

The square root of 21228 is about 145.6983184529. The cubic root of 21228 is about 27.6887293572.

The spelling of 21228 in words is "twenty-one thousand, two hundred twenty-eight".

Divisors: 1 2 3 4 6 12 29 58 61 87 116 122 174 183 244 348 366 732 1769 3538 5307 7076 10614 21228