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21321664 = 267213523
BaseRepresentation
bin101000101010…
…1011111000000
31111010020211021
41101111133000
520424243124
62040555224
7346142200
oct121253700
944106737
1021321664
1111043311
127182b14
134556b90
142b90400
151d127e4
hex14557c0

21321664 has 84 divisors (see below), whose sum is σ = 53105304. Its totient is φ = 8418816.

The previous prime is 21321661. The next prime is 21321683. The reversal of 21321664 is 46612312.

It is a super-2 number, since 2×213216642 = 909226711457792, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321661) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 40507 + ... + 41029.

It is an arithmetic number, because the mean of its divisors is an integer number (632206).

Almost surely, 221321664 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 21321664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26552652).

21321664 is an abundant number, since it is smaller than the sum of its proper divisors (31783640).

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

21321664 is a wasteful number, since it uses less digits than its factorization.

21321664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 562 (or 545 counting only the distinct ones).

The product of its digits is 1728, while the sum is 25.

The square root of 21321664 is about 4617.5387383324. The cubic root of 21321664 is about 277.2939313681.

Adding to 21321664 its reverse (46612312), we get a palindrome (67933976).

The spelling of 21321664 in words is "twenty-one million, three hundred twenty-one thousand, six hundred sixty-four".

Divisors: 1 2 4 7 8 13 14 16 26 28 32 49 52 56 64 91 98 104 112 182 196 208 224 364 392 416 448 523 637 728 784 832 1046 1274 1456 1568 2092 2548 2912 3136 3661 4184 5096 5824 6799 7322 8368 10192 13598 14644 16736 20384 25627 27196 29288 33472 40768 47593 51254 54392 58576 95186 102508 108784 117152 190372 205016 217568 234304 333151 380744 410032 435136 666302 761488 820064 1332604 1522976 1640128 2665208 3045952 5330416 10660832 21321664