2,800

[History]  Tennessee is commonly known as the Volunteer State since 1847, when the governor called for 2,800 volunteers for the Mexican War and 30,000 men responded.

 

2,801

[Math.]  A prime number.

 

[Math.]  Seven square numbers using the same digits: 10242 = 1,048,576; 10282 = 1,056,784; 10422 = 1,085,764; 23962 = 5,740,816; 24012 = 5,764,801; 25992 = 6,754,801 and 28012 = 7,845,601.

 

2,821 

[Math.]  The 5th Carmichael number: 2821 = 7×13×31.

 

2,850

[History]   Fu-Hi became the first Emperor of China in the year 2850 B.C.E. (To be checked).

 

2,850

[Math.]  A triangular number (sum of all integers from 1 to 75): 2850 = 1+2+…+74+75.

 

2,856

[Math.]  28563 = 2133+…+5553 = 2733+…+5603 = 23,295,638,016. The smallest number whose cube can be expressed as a sum of a sequence of cube numbers in two different ways.

 

2,858

[Math.]  28582 = 8,168,164.

 

2,870

[Math.]  A pyramidal number (sum of all squares of integers from 1 to 20): 2870 = 12+22+…+192+202.

 

2,880

[Math.]  Sum (in degrees) of all internal angles of an 18-side polygon.

 

[Measure]  The number of drops in a cup.

U.S. customary units for kitchen measurements: ½ pints = 1 cup = 8 fluid ounces = 16 tablespoons = 48 teaspoons = 2880 drops = 236.588 ml.

 

2,897

[Math.]  A prime number.  The first Markov numbers are 1, 2, 5, 13, 29, 34, 89, 169, 194, 233, 433, 610, 985, 1325, 1597, 2897, 4181, 5741, 6466, 7561, 9077…