Orst, 18 bytes
κñˋςᏓ{ᏓĖΐÇ}Ñδ As hex bytes, this is
DE 87 FF D0 E7 FF 47 FF A0 FF 47 18 DD 0E FF A5 2F D4 Encoding as UTF-8:
Þ‡ÿÐçÿGÿ ÿGÝÿ¥ÿGÝÿ¥/Ô How it works
κñˋςᏓ{ᏓĖΐÇ}Ñδ - Full program. Takes b, then a κ - Save b in variable $x ñˋ - Remove and swap. Stack is [a] ςᏓ - Base-and-powers; Prime decomposition of a { }Ñ - Over each pair: ᏓĖ - Reduce by power ΐ - Retrieve b Ç - Less than or equal? δ - True for all?