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21021220 = 225111947107
BaseRepresentation
bin101000000110…
…0001000100100
31110112222200201
41100030020210
520340134340
62030320244
7343451233
oct120141044
943488621
1021021220
1110958610
127059084
1344801bc
142b12b1a
151ca379a
hex140c224

21021220 has 96 divisors (see below), whose sum is σ = 52254720. Its totient is φ = 7021440.

The previous prime is 21021181. The next prime is 21021229. The reversal of 21021220 is 2212012.

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a junction number, because it is equal to n+sod(n) for n = 21021197 and 21021206.

It is not an unprimeable number, because it can be changed into a prime (21021229) 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 31 ways as a sum of consecutive naturals, for example, 196407 + ... + 196513.

It is an arithmetic number, because the mean of its divisors is an integer number (544320).

Almost surely, 221021220 is an apocalyptic number.

21021220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21021220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26127360).

21021220 is an abundant number, since it is smaller than the sum of its proper divisors (31233500).

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

21021220 is a wasteful number, since it uses less digits than its factorization.

21021220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 193 (or 191 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 10.

The square root of 21021220 is about 4584.8904021798. The cubic root of 21021220 is about 275.9853139284.

Adding to 21021220 its reverse (2212012), we get a palindrome (23233232).

The spelling of 21021220 in words is "twenty-one million, twenty-one thousand, two hundred twenty".

Divisors: 1 2 4 5 10 11 19 20 22 38 44 47 55 76 94 95 107 110 188 190 209 214 220 235 380 418 428 470 517 535 836 893 940 1034 1045 1070 1177 1786 2033 2068 2090 2140 2354 2585 3572 4066 4180 4465 4708 5029 5170 5885 8132 8930 9823 10058 10165 10340 11770 17860 19646 20116 20330 22363 23540 25145 39292 40660 44726 49115 50290 55319 89452 95551 98230 100580 110638 111815 191102 196460 221276 223630 276595 382204 447260 477755 553190 955510 1051061 1106380 1911020 2102122 4204244 5255305 10510610 21021220