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21640080 = 24357111171
BaseRepresentation
bin101001010001…
…1001110010000
31111201102121110
41102203032100
521014440310
62051453320
7351636420
oct122431620
944642543
1021640080
1111240570
1272b7240
134638aa7
142c34480
151d76d20
hex14a3390

21640080 has 160 divisors (see below), whose sum is σ = 83708928. Its totient is φ = 4492800.

The previous prime is 21640067. The next prime is 21640081. The reversal of 21640080 is 8004612.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21640081) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 17895 + ... + 19065.

Almost surely, 221640080 is an apocalyptic number.

21640080 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 21640080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (41854464).

21640080 is an abundant number, since it is smaller than the sum of its proper divisors (62068848).

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

21640080 is a wasteful number, since it uses less digits than its factorization.

21640080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1205 (or 1199 counting only the distinct ones).

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 21640080 is about 4651.8899385089. The cubic root of 21640080 is about 278.6674781028.

Adding to 21640080 its reverse (8004612), we get a palindrome (29644692).

The spelling of 21640080 in words is "twenty-one million, six hundred forty thousand, eighty".

Divisors: 1 2 3 4 5 6 7 8 10 11 12 14 15 16 20 21 22 24 28 30 33 35 40 42 44 48 55 56 60 66 70 77 80 84 88 105 110 112 120 132 140 154 165 168 176 210 220 231 240 264 280 308 330 336 385 420 440 462 528 560 616 660 770 840 880 924 1155 1171 1232 1320 1540 1680 1848 2310 2342 2640 3080 3513 3696 4620 4684 5855 6160 7026 8197 9240 9368 11710 12881 14052 16394 17565 18480 18736 23420 24591 25762 28104 32788 35130 38643 40985 46840 49182 51524 56208 64405 65576 70260 77286 81970 90167 93680 98364 103048 122955 128810 131152 140520 154572 163940 180334 193215 196728 206096 245910 257620 270501 281040 309144 327880 360668 386430 393456 450835 491820 515240 541002 618288 655760 721336 772860 901670 983640 1030480 1082004 1352505 1442672 1545720 1803340 1967280 2164008 2705010 3091440 3606680 4328016 5410020 7213360 10820040 21640080