671760

Appears in sequences

• Number of noninvertible 2 X 2 matrices over Z/nZ (determinant is a divisor of 0).at n=28A020479
• Balanced refactorable numbers.at n=26A078543
• Numbers n such that sigma(n) = 13*phi(n) (where sigma=A000203, phi=A000010).at n=17A171258