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18181812 = 22311181761
BaseRepresentation
bin100010101011…
…0111010110100
31021012201202110
41011112322310
514123304222
61445411020
7310354125
oct105267264
937181673
1018181812
11a2992a0
126109a70
1339c798c
1425b404c
1518e230c
hex1156eb4

18181812 has 48 divisors (see below), whose sum is σ = 46597824. Its totient is φ = 5472000.

The previous prime is 18181783. The next prime is 18181817. The reversal of 18181812 is 21818181.

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

It is a self number, because there is not a number n which added to its sum of digits gives 18181812.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18181817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23512 + ... + 24272.

It is an arithmetic number, because the mean of its divisors is an integer number (970788).

Almost surely, 218181812 is an apocalyptic number.

18181812 is a gapful number since it is divisible by the number (12) 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 18181812, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23298912).

18181812 is an abundant number, since it is smaller than the sum of its proper divisors (28416012).

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

18181812 is a wasteful number, since it uses less digits than its factorization.

18181812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 960 (or 958 counting only the distinct ones).

The product of its digits is 1024, while the sum is 30.

The square root of 18181812 is about 4264.0136022297. The cubic root of 18181812 is about 262.9535596315.

Adding to 18181812 its reverse (21818181), we get a palindrome (39999993).

The spelling of 18181812 in words is "eighteen million, one hundred eighty-one thousand, eight hundred twelve".

Divisors: 1 2 3 4 6 11 12 22 33 44 66 132 181 362 543 724 761 1086 1522 1991 2172 2283 3044 3982 4566 5973 7964 8371 9132 11946 16742 23892 25113 33484 50226 100452 137741 275482 413223 550964 826446 1515151 1652892 3030302 4545453 6060604 9090906 18181812