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21243040 = 2557131459
BaseRepresentation
bin101000100001…
…0010010100000
31110222020222021
41101002102200
520414234130
62035151224
7345364030
oct121022240
943866867
1021243040
1110a9a235
127145514
13452a160
142b6d8c0
151ce937a
hex14424a0

21243040 has 96 divisors (see below), whose sum is σ = 61810560. Its totient is φ = 6718464.

The previous prime is 21243023. The next prime is 21243049. The reversal of 21243040 is 4034212.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243049) 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 15 ways as a sum of consecutive naturals, for example, 13831 + ... + 15289.

It is an arithmetic number, because the mean of its divisors is an integer number (643860).

Almost surely, 221243040 is an apocalyptic number.

21243040 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 21243040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30905280).

21243040 is an abundant number, since it is smaller than the sum of its proper divisors (40567520).

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

21243040 is a wasteful number, since it uses less digits than its factorization.

21243040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1494 (or 1486 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 16.

The square root of 21243040 is about 4609.0172488286. The cubic root of 21243040 is about 276.9526695188.

Adding to 21243040 its reverse (4034212), we get a palindrome (25277252).

The spelling of 21243040 in words is "twenty-one million, two hundred forty-three thousand, forty".

Divisors: 1 2 4 5 7 8 10 13 14 16 20 26 28 32 35 40 52 56 65 70 80 91 104 112 130 140 160 182 208 224 260 280 364 416 455 520 560 728 910 1040 1120 1456 1459 1820 2080 2912 2918 3640 5836 7280 7295 10213 11672 14560 14590 18967 20426 23344 29180 37934 40852 46688 51065 58360 75868 81704 94835 102130 116720 132769 151736 163408 189670 204260 233440 265538 303472 326816 379340 408520 531076 606944 663845 758680 817040 1062152 1327690 1517360 1634080 2124304 2655380 3034720 4248608 5310760 10621520 21243040