Number Gossip

(Enter a number and I'll tell you everything you wanted to know about it but were afraid to ask.)

Unique Properties of 315

  • 315 is the smallest n such that φ(n-1) + φ(n+1) = σ(n)/2
  • 315 is the smallest squareful order of a cyclotomic polynomial containing a coefficient with an absolute value greater than one
  • 315 is the smallest odd number such that its sum of divisors is larger than the sums of divisors of its neighbors

Common Properties of 315