Which number is bigger than the others? Which number is bigger?
$2^{431},3^{421},4^{321},21^{43},31^{42}$
My attempt:
$4^{321}=2^{642}>2^{431},4^{321}=2^{642}>2^{640}=32^{128}>31^{42}$
$3^{421}>3^{420}=27^{140}>21^43$
But I don't know how to compare $4^{321}$ and $3^{421}$ Any hints?

$4^{321}=2^{642}=2^{11*58+4}=16*2048^{58}<27*2187^{58}=3^3*3^{7*58}=3^{409}<3^{421}$
