This article is about the integer. For the telephone number, see 555 (telephone number). For other uses, see 555 (disambiguation).

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:

.

It is the twenty-sixth number such that its Euler totient (288) is equal to the totient value of its sum-of-divisors: .[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.


Allikas: https://en.wikipedia.org/wiki/555_(number)
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