# 8999

This number is a prime. A prime number whose sum of digits (sod) is greater than or equal to the near-repdigit prime 8999 must be titanic.

```The smallest prime numbers whose sum of digits equals the n-th prime:

1 -> sod(2)=2 [Honaker]
2 -> sod(3)=3 [Honaker]
3 -> sod(5)=5 [Honaker]
4 -> sod(7)=7 [Honaker]
5 -> sod(29)=11 [Honaker]
6 -> sod(67)=13 [Honaker]
7 -> sod(89)=17 [Honaker]
8 -> sod(199)=19 [Honaker]
9 -> sod(599)=23 [Honaker]
10 -> sod(2999)=29 [Honaker]
11 -> sod(4999)=31 [Honaker]
12 -> sod(29989)=37 [Chua]
13 -> sod(59999)=41 [Chua]
14 -> sod(79999)=43 [Chua]
15 -> sod(389999)=47 [Chua]
16 -> sod(989999)=53 [Chua]
17 -> sod(6999899)=59 [Chua]
18 -> sod(8989999)=61 [Chua]
19 -> sod(59899999)=67 [Chua]
20 -> sod(89999999)=71 [Chua]
21 -> sod(289999999)=73 [Chua]
22 -> sod(799999999)=79 [Chua]
23 -> sod(3999998999)=83 [Chua]
24 -> sod(18989999999)=89 [Gaydos]
25 -> sod(79999999999)=97 [Marcus]
26 -> sod(399999998999)=101 [Marcus]
27 -> sod(599999899999)=103 [Marcus]
28 -> sod(999998999999)=107 [Wilson]
29 -> sod(2999998999999)=109 [Luhn]
30 -> sod(6999998999999)=113 [Gaydos]
31 -> sod(299999989999999)=127 [Gaydos]
32 -> sod(789989999999999)=131 [Gaydos]
33 -> sod(3999999999999989)=137 [Gaydos]
34 -> sod(5999999999899999)=139 [Gaydos]
35 -> sod(69989999999999999)=149 [Gaydos]
36 -> sod(89989999999999999)=151 [Gaydos]
37 -> sod(599999999999899999)=157 [Rivera]
38 -> sod(2999998999999999999)=163 [Rivera]
39 -> sod(7799999999999999999)=167 [Gaydos]
40 -> sod(29999999999999999999)=173 [Bajpai]
41 -> sod(89999999999999999999)=179 [Bajpai]
42 -> sod(299999899999999999999)=181 [Gupta]
43 -> sod(4799999999999999999999)=191 [Gupta]
44 -> sod(5899999999999999999999)=193 [Gupta]
45 -> sod(9998999999999999999999)=197 [Bajpai]
46 -> sod(29998999999999999999999)=199 [Gaydos]
47 -> sod(599999999999899999999999)=211 [Gupta]
48 -> sod(17989999999999999999999999)=223 [Gaydos]
49 -> sod(39998999999999999999999999)=227 [Gupta]
50 -> sod(59999999999899999999999999)=229 [Gupta]
51 -> sod(99999999999999998999999999)=233 [Rivera]
52 -> sod(698999999999999999999999999)=239 [Gupta]
53 -> sod(899999998999999999999999999)=241 [Gupta]
54 -> sod(18899999999999999999999999999)=251 [Gupta]
55 -> sod(59999999999999999999999999999)=257 [Gupta]
56 -> sod(489999999899999999999999999999)=263 [Gaydos]
57 -> sod(899999999999999999999999999999)=269 [Gupta]
58 -> sod(2999999999999999999999989999999)=271 [Gupta]
59 -> sod(8999899999999999999999999999999)=277 [Gupta]
.
.
.
1117 -> sod(see number)=8999. [Bajpai]
``` (8999, 9001) is the only case of twin primes less than a googol of form (9*10^n-1, 9*10^n+1). [Loungrides] Warning: Do not subtract the prime number 8999 from its reversal and turn the difference upside down. [Heath] The largest four-digit near-repdigit prime is the reversal of the largest four-digit semiprime. [Silva] 8999 followed by seventy-two 3's is a prime whose sum of digits equals the prime 251. [Bajpai]

(There are 2 curios for this number that have not yet been approved by an editor.)