| Number: | 555 |
555 (five hundred [and] fifty-five) is the natural number following 554 and preceding 556.
555 is a sphenic number. In base 10, 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.
It is the sum of the first triplet of three-digit permutable primes in decimal:
113+131+311=555
It is the twenty-sixth number such that its Euler totient (288) is equal to the totient value of its sum-of-divisors:
\varphi(555)=\varphi(\sigma(555))