In mathematics, a sparsely totient number is a certain kind of even natural number. A natural number, n, is sparsely totient if for any m > n,

φ(m)>φ(n),

where φ is Euler's totient function. The first few sparsely totient numbers are:

2, 6, 12, 18, 30, 42, 60, 66, 90, 120, 126, 150, 210, 240, 270, 330, 420, 462, 510, 630.

These are listed in .

Numbers