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21684860 = 22517234759
BaseRepresentation
bin101001010111…
…0001001111100
31111210201000222
41102232021330
521022403420
62052440512
7352214111
oct122561174
944721028
1021684860
111127117a
127319138
1346532a2
142c46908
151d85225
hex14ae27c

21684860 has 96 divisors (see below), whose sum is σ = 52254720. Its totient is φ = 7513088.

The previous prime is 21684853. The next prime is 21684863. The reversal of 21684860 is 6848612.

It is a self number, because there is not a number n which added to its sum of digits gives 21684860.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21684863) 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 31 ways as a sum of consecutive naturals, for example, 367511 + ... + 367569.

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

Almost surely, 221684860 is an apocalyptic number.

21684860 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 21684860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26127360).

21684860 is an abundant number, since it is smaller than the sum of its proper divisors (30569860).

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

21684860 is a wasteful number, since it uses less digits than its factorization.

21684860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 155 (or 153 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 35.

The square root of 21684860 is about 4656.7005486718. The cubic root of 21684860 is about 278.8595619907.

The spelling of 21684860 in words is "twenty-one million, six hundred eighty-four thousand, eight hundred sixty".

Divisors: 1 2 4 5 10 17 20 23 34 46 47 59 68 85 92 94 115 118 170 188 230 235 236 295 340 391 460 470 590 782 799 940 1003 1081 1180 1357 1564 1598 1955 2006 2162 2714 2773 3196 3910 3995 4012 4324 5015 5405 5428 5546 6785 7820 7990 10030 10810 11092 13570 13865 15980 18377 20060 21620 23069 27140 27730 36754 46138 47141 55460 63779 73508 91885 92276 94282 115345 127558 183770 188564 230690 235705 255116 318895 367540 461380 471410 637790 942820 1084243 1275580 2168486 4336972 5421215 10842430 21684860