555 (five hundred
ndfifty-five) is the
natural number
In mathematics, the natural numbers are the numbers 0, 1, 2, 3, and so on, possibly excluding 0. Some start counting with 0, defining the natural numbers as the non-negative integers , while others start with 1, defining them as the positive in ...
following
554 and preceding
556.
In mathematics
555 is a
sphenic number. In
base 10
The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers (''decimal fractions'') of t ...
, it is a
repdigit, and because it is divisible by the sum of its digits, it is a
Harshad number. It is also a Harshad number in
binary, base 11, base 13 and
hexadecimal
Hexadecimal (also known as base-16 or simply hex) is a Numeral system#Positional systems in detail, positional numeral system that represents numbers using a radix (base) of sixteen. Unlike the decimal system representing numbers using ten symbo ...
.
555 is a Harshad number as 555 ÷ (5+5+5) is 555 ÷ 15 is
37..
Also, 555 is unique because it is not just a multiple of 5+5+5 (15) but that 15 is divisible by it’s triangular order.
It is the sum of the first triplet of three-digit
permutable primes in
decimal
The decimal numeral system (also called the base-ten positional numeral system and denary or decanary) is the standard system for denoting integer and non-integer numbers. It is the extension to non-integer numbers (''decimal fractions'') of th ...
:
:
.
It is the twenty-sixth number such that its
Euler totient (
288) is equal to the totient value of its
sum-of-divisors:
.
References
External links
*
Integers
{{Num-stub