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21081000 = 233537027
BaseRepresentation
bin101000001101…
…0101110101000
31110200000200210
41100122232220
520344043000
62031501120
7344120433
oct120325650
943600623
1021081000
1110999516
1270877a0
1344a1485
142b2a81a
151cb6350
hex141aba8

21081000 has 64 divisors (see below), whose sum is σ = 65782080. Its totient is φ = 5620800.

The previous prime is 21080987. The next prime is 21081017. The reversal of 21081000 is 18012.

It is a happy number.

It is a super-2 number, since 2×210810002 = 888817122000000, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 514 + ... + 6513.

It is an arithmetic number, because the mean of its divisors is an integer number (1027845).

Almost surely, 221081000 is an apocalyptic number.

21081000 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 21081000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32891040).

21081000 is an abundant number, since it is smaller than the sum of its proper divisors (44701080).

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

21081000 is a wasteful number, since it uses less digits than its factorization.

21081000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7051 (or 7037 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 21081000 is about 4591.4050137186. The cubic root of 21081000 is about 276.2466813685.

Adding to 21081000 its reverse (18012), we get a palindrome (21099012).

The spelling of 21081000 in words is "twenty-one million, eighty-one thousand".

Divisors: 1 2 3 4 5 6 8 10 12 15 20 24 25 30 40 50 60 75 100 120 125 150 200 250 300 375 500 600 750 1000 1500 3000 7027 14054 21081 28108 35135 42162 56216 70270 84324 105405 140540 168648 175675 210810 281080 351350 421620 527025 702700 843240 878375 1054050 1405400 1756750 2108100 2635125 3513500 4216200 5270250 7027000 10540500 21081000