# 555 (number)

 ← 554 555 556 →
Cardinalfive hundred fifty-five
Ordinal555th
(five hundred fifty-fifth)
Factorization3 × 5 × 37
Greek numeralΦΝΕ´
Roman numeralDLV
Binary10001010112
Ternary2021203
Senary23236
Octal10538
Duodecimal3A312

555 (five hundred [and] fifty-five) is the natural number following 554 and preceding 556.

## In mathematics

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:

${\displaystyle 113+131+311=555}$.

It is the twenty-sixth number such that its Euler totient (288) is equal to the totient value of its sum-of-divisors: ${\displaystyle \varphi (555)=\varphi (\sigma (555))}$.[1]

## References

1. ^ Sloane, N. J. A. (ed.). "Sequence A006872 (Numbers k such that phi(k) is phi(sigma(k)).)". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2023-08-31.