core/homeassistant/components/input_number/icons.json

{
  "services": {
    "decrement": {
      "service": "mdi:minus"
    },
    "increment": {
      "service": "mdi:plus"
    },
    "set_value": {
      "service": "mdi:numeric"
    },
    "reload": {
      "service": "mdi:reload"
    }
  }
}