.box {
--d:4deg; /* distance between dashes */
--n:30; /* number of dashes */
--b:2px; /* control the thickness of border*/
width: 180px;
display:inline-flex;
justify-content:center;
align-items:center;
font-size:35px;
border-radius:50%;
position:relative;
}
.box::after {
content:"";
position:absolute;
top:0;
left:0;
right:0;
bottom:0;
z-index:-1;
border-radius:inherit;
background:var(--c,linear-gradient(red,blue));
-webkit-mask:
radial-gradient(farthest-side,transparent calc(100% - var(--b)),#fff calc(100% - var(--b) + 1px)),
repeating-conic-gradient(#000 0 calc(360deg/var(--n) - var(--d)),transparent 0 calc(360deg/var(--n)));
-webkit-mask-composite: source-in;
mask:
radial-gradient(farthest-side,transparent calc(100% - var(--b)),#fff calc(100% - var(--b) + 1px)),
repeating-conic-gradient(#000 0 calc(360deg/var(--n) - var(--d)),transparent 0 calc(360deg/var(--n)));
mask-composite: intersect;
}
/* keep the element square */
.box:before {
content:"";
padding-top:100%;
}
body {
background:linear-gradient(to right,yellow,pink);
}
<div class="box">19</div>
<div class="box" style="--n:20;--b:5px;width:150px;--c:conic-gradient(green,orange,black)">17</div>
<div class="box" style="--n:8;--d:20deg;--b:10px;width:130px;--c:conic-gradient(black,white,black)">5</div>
<div class="box" style="--n:18;--d:12deg;--b:8px;width:100px;--c:linear-gradient(60deg,red 50%,green 0)">9</div>
<div class="box" style="--n:10;--d:20deg;--b:3px;width:100px;--c:#fff">13</div>