I'm assuming you need this rounded in scientific notation format.
First you have to determine how many significant numbers are there. Non zero numbers are significant and leading zeros are NOT significant. So in this case 7,4,6,9,1, and 5 are significant numbers and 0 is not. Thus there are 6 significant numbers.
Normally what you would do is move the decimal place over 6 times since there are 6 significant digits. However, in this case doing so would put the decimal at the end of the number which makes no sense. So it must be written in another format which gives;