Children's spontaneous focusing on Arabic number symbols (SFONS) has been identified as a relevant component of their early mathematical development. This study investigated whether SFONS is a separate construct from spontaneous focusing on numerosity (SFON) and examined whether it is uniquely related to numerical abilities and mathematics achievement. Participants were 159 kindergartners (4-5-year-olds) who completed measures of SFONS, SFON, numerical abilities, mathematics achievement, spatial ability, and language ability. Confirmatory factor analysis revealed that a two-factor model representing a separate SFONS and SFON factor best fitted the data, indicating that SFONS is separate from SFON. Correlation and regression analyses showed that SFONS was associated with numerical abilities and mathematics achievement. These associations -- except for verbal counting -- remained after controlling for age, parental education, spatial ability, language ability, and SFON. These findings suggest that SFONS is a unique component of early mathematical development that deserves attention in early mathematics education.