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999989991 = 32721113101157
BaseRepresentation
bin111011100110101…
…010001011100111
32120200122202101100
4323212222023213
54021444134431
6243121131143
733531526500
oct7346521347
92520582340
10999989991
11473517310
1223aa89ab3
1312c235770
1496b47ba7
155cbcd4e6
hex3b9aa2e7

999989991 has 144 divisors (see below), whose sum is σ = 2006248608. Its totient is φ = 471744000.

The previous prime is 999989981. The next prime is 999990011. The reversal of 999989991 is 199989999.

It can be divided in two parts, 999989 and 991, that multiplied together give a palindrome (990989099).

It is a happy number.

It is not a de Polignac number, because 999989991 - 27 = 999989863 is a prime.

999989991 is a modest number, since divided by 89991 gives 9999 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999989981) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 6369285 + ... + 6369441.

It is an arithmetic number, because the mean of its divisors is an integer number (13932282).

Almost surely, 2999989991 is an apocalyptic number.

999989991 is a gapful number since it is divisible by the number (91) formed by its first and last digit.

999989991 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

999989991 is a wasteful number, since it uses less digits than its factorization.

999989991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 302 (or 292 counting only the distinct ones).

The product of its digits is 38263752, while the sum is 72.

The square root of 999989991 is about 31622.6183451023. The cubic root of 999989991 is about 999.9966636555.

The spelling of 999989991 in words is "nine hundred ninety-nine million, nine hundred eighty-nine thousand, nine hundred ninety-one".

Divisors: 1 3 7 9 11 13 21 33 39 49 63 77 91 99 101 117 143 147 157 231 273 303 429 441 471 539 637 693 707 819 909 1001 1099 1111 1287 1313 1413 1617 1727 1911 2041 2121 3003 3297 3333 3939 4851 4949 5181 5733 6123 6363 7007 7693 7777 9009 9191 9891 9999 11817 12089 14287 14443 14847 15543 15857 18369 21021 22451 23079 23331 27573 36267 42861 43329 44541 47571 54439 63063 64337 67353 69237 69993 82719 84623 100009 101101 108801 110999 128583 129987 142713 157157 163317 174427 193011 202059 206141 253869 300027 303303 332997 471471 489951 523281 579033 618423 707707 761607 776993 900081 909909 998991 1100099 1220989 1414413 1442987 1569843 1855269 2123121 2267551 2330979 3300297 3662967 4328961 6369363 6802653 6992937 8546923 9900891 10100909 10988901 12986883 15872857 20407959 25640769 30302727 47618571 76922307 90908181 111109999 142855713 333329997 999989991