Is mean significant and not abnormal?

Hi everyone!
I am having some troubles with interpreting the significance of mean.
Mean= 0.19609
St. Dev=0.12341
n=141
I get t-statistic of 18.86763( ratio mean/ st. error)
I thought that for the mean to be significant and expected (not abnormal) t-stat has to be within the interval -1.645<t<1.645 with 95% level of confidence.. or am I wrong?
How do I explain enormous t-statistic, does it make any sense at all?
Thank you