840 (number)
840 is the natural number following 839 and preceding 841.Mathematical Properties
- It is an even number.
- It is a practical number.
- It is a congruent number.
- It is a highly composite number, with 32 divisors : 1, 2, 3, 4, 5, 6, 7, 8, 10, 12, 14, 15, 20, 21, 24, 28, 30, 35, 40, 42, 56, 60, 70, 84, 105, 120, 140, 168, 210, 280, 420, 840. Since the sum of its divisors 2040 > 840
- it is an abundant number and also a superabundant number,
- It is an idoneal number,
- It is the least common multiple of 1, 2, 3, 4, 5, 6, 7, 8.
- It is the largest number k such that all coprime quadratic residues modulo k are squares. In this case, they are 1, 121, 169, 289, 361 and 529.
- It is an evil number.
- It is a palindrome number and a repdigit number repeated in the positional numbering system in base 29 and in that in base 34.
