800 is the natural number following 799 and preceding 801 .

Ordinal	Eight hundred
Cardinal	800th
Factorization
Roman numeral	DCCC
Binary	1100100000
Hexadecimal	320

It is the sum of four consecutive primes (193 + 197 + 199 + 211). It is a Harshad number.

Eight hundred is also:

• The telephone area code for toll-free phone calls in the North American Numbering Plan and some other countries.
• The international direct dial code for toll-free international phone calls.
• In the ISO rating standard (aka ISO 5800), a common film speed for photographic films.
• The flight number of TWA Flight 800

For the year AD, see 800.

801 = 3² × 89, Harshad number

802 = 2 × 401, sum of eight consecutive primes (83 + 89 + 97 + 101 + 103 + 107 + 109 + 113), nontotient, also the telephone area code for American state of Vermont

803 = 11 × 73, sum of three consecutive primes (263 + 269 + 271), sum of nine consecutive primes (71 + 73 + 79 + 83 + 89 + 97 + 101 + 103 + 107), Harshad number

804 = 2² × 3 × 67, nontotient, Harshad number

805 = 5 × 7 × 23

806 = 2 × 13 × 31, sphenic number, nontotient

807 = 3 × 269

808 = 2³ × 101, also the telephone area code for the American state of Hawaii

809 prime number, Sophie Germain prime

810 = 2 × 3⁴ × 5, Harshad number

811 prime number, sum of five consecutive primes (151 + 157 + 163 + 167 + 173), Mertens function(811) returns 0

812 = 2² × 7 × 29, pronic number, Mertens function(812) returns 0

813 = 3 × 271

814 = 2 × 11 × 37, sphenic number, Mertens function(814) returns 0, nontotient

815 = 5 × 163

816 = 2⁴ × 3 × 17, tetrahedral number

817 = 19 × 43, sum of three consecutive primes (269 + 271 + 277), centered hexagonal number

818 = 2 × 409, nontotient

819 = 3² × 7 × 13, square pyramidal number

820 = 2² × 5 × 41, triangular number, Harshad number

821 prime number

822 = 2 × 3 × 137, sphenic number

823 prime number, Mertens function(823) returns 0

824 = 2³ × 103, sum of ten consecutive primes (61 + 67 + 71 + 73 + 79 + 83 + 89 + 97 + 101 + 103), Mertens function(824) returns 0, nontotient

825 = 3 × 5² × 11, Smith number, Mertens function(825) returns 0, Harshad number

826 = 2 × 7 × 59, sphenic number

827 prime number, sum of seven consecutive primes (103 + 107 + 109 + 113 + 127 + 131 + 137)

828 = 2² × 3² × 23, Harshad number

829 prime number, sum of three consecutive primes (271 + 277 + 281)

830 = 2 × 5 × 83, sphenic number, sum of four consecutive primes (197 + 199 + 211 + 223), nontotient

831 = 3 × 277

832 = 2⁶ × 13, Harshad number

833 = 7² × 17

834 = 2 × 3 × 139, sphenic number, sum of six consecutive primes (127 + 131 + 137 + 139 + 149 + 151), nontotient

835 = 5 × 167, Motzkin number

836 = 2² × 11 × 19, weird number

837 = 3³ × 31

838 = 2 × 419

839 prime number, safe prime, sum of five consecutive primes (157 + 163 + 167 + 173 + 179), highly cototient number

840 = 2³ × 3 × 5 × 7, smallest numbers divisible by the numbers 1 to 8, Harshad number in base 2 thru base 10

841 = 29² = 20² + 21², sum of three consecutive primes (277 + 281 + 283), sum of nine consecutive primes (73 + 79 + 83 + 89 + 97 + 101 + 103 + 107 + 109), centered square number, centered heptagonal number, centered octagonal number

842 = 2 × 421, nontotient

843 = 3 × 281

844 = 2² × 211, nontotient

845 = 5 × 13²

846 = 2 × 3² × 47, sum of eight consecutive primes (89 + 97 + 101 + 103 + 107 + 109 + 113 + 127), nontotient, Harshad number

847 = 7 × 11²

848 = 2⁴ × 53

849 = 3 × 283, Mertens function(849) returns 0

850 = 2 × 5² × 17, Mertens function(850) returns 0, nontotient

851 = 23 × 37

852 = 2² × 3 × 71, Smith number

853 prime number, Mertens function(853) returns 0

854 = 2 × 7 × 61, nontotient

855 = 3² × 5 × 19, decagonal number, centered cube number

856 = 2³ × 107, nonagonal number, centered pentagonal number

857 prime number, sum of three consecutive primes (281 + 283 + 293)

858 = 2 × 3 × 11 × 13, Giuga number

859 prime number

860 = 2² × 5 × 43, sum of four consecutive primes (199 + 211 + 223 + 227)

861 = 3 × 7 × 41, sphenic number, triangular number, hexagonal number, Smith number

862 = 2 × 431

863 prime number, safe prime, sum of five consecutive primes (163 + 167 + 173 + 179 + 181), sum of seven consecutive primes (107 + 109 + 113 + 127 + 131 + 137 + 139)

864 = 2⁵ × 3³, sum of a twin prime (431 + 433), sum of six consecutive primes (131 + 137 + 139 + 149 + 151 + 157), Harshad number

865 = 5 × 173

866 = 2 × 433, nontotient

867 = 3 × 17², also the telephone area code for Yukon, Northwest Territories and Nunavut

868 = 2² × 7 × 31, nontotient

869 = 11 × 79, Mertens function(869) returns 0

870 = 2 × 3 × 5 × 29, sum of ten consecutive primes (67 + 71 + 73 + 79 + 83 + 89 + 97 + 101 + 103 + 107), pronic number, nontotient, Harshad number

This number is the magic constant of nxn magic square and n-Queens Problem for n = 12.

871 = 13 × 67

872 = 2³ × 109, nontotient

873 = 3² × 97

874 = 2 × 19 × 23, sum of the first twenty-three primes, nontotient, Harshad number

875 = 5³ × 7

876 = 2² × 3 × 73

877 prime number, Bell number, Mertens function(877) returns 0

878 = 2 × 439, nontotient

879 = 3 × 293

880 = 2⁴ × 5 × 11, Harshad number; 148-gonal number; the number of nxn magic squares for n = 4.

881 prime number, sum of nine consecutive primes (79 + 83 + 89 + 97 + 101 + 103 + 107 + 109 + 113)

882 = 2 × 3² × 7², Harshad number

883 prime number, sum of three consecutive primes (283 + 293 + 307), Mertens function(883) returns 0

884 = 2² × 13 × 17, Mertens function(884) returns 0

885 = 3 × 5 × 59, sphenic number

886 = 2 × 443, Mertens function(886) returns 0

887 prime number, safe prime

888 = 2³ × 3 × 37, sum of eight consecutive primes (97 + 101 + 103 + 107 + 109 + 113 + 127 + 131), Harshad number

Also direct dial code for toll-free phone calls in the US.

889 = 7 × 127, Mertens function(889) returns 0

890 = 2 × 5 × 89, sphenic number, sum of four consecutive primes (211 + 223 + 227 + 229), nontotient

891 = 3⁴ × 11, sum of five consecutive primes (167 + 173 + 179 + 181 + 191), octahedral number

892 = 2² × 223, nontotient

893 = 19 × 47, Mertens function(893) returns 0

894 = 2 × 3 × 149, sphenic number, nontotient

895 = 5 × 179, Smith number, Woodall number, Mertens function(895) returns 0

896 = 2⁷ × 7, sum of six consecutive primes (137 + 139 + 149 + 151 + 157 + 163), Mertens function(896) returns 0

897 = 3 × 13 × 23, sphenic number

898 = 2 × 449, Mertens function(898) returns 0, nontotient

899 = 29 × 31