50/100 hand against mahatma at UB

[Keres]

UB 50/100 NL Hold'em

Random Player A is at seat 0 with $4648.
Hero is at seat 3 with $12034.50.
Random Player B is at seat 5 with $13425.
Random Player C is at seat 6 with $9100.
Mahatma is at seat 7 with $17187.
The button is at seat 5.

Preflop: Hero is CO with K[img]/images/graemlins/heart.gif[/img] A [img]/images/graemlins/club.gif[/img]
UTG Folds, Hero raises to $350, Button folds, SB folds, BB (Mahatma) calls

Flop: ($750) 10[img]/images/graemlins/club.gif[/img] K[img]/images/graemlins/diamond.gif[/img] 3[img]/images/graemlins/spade.gif[/img]
Mahatma checks. Hero bets $500. Mahatma calls.

Turn: ($1750) 5[img]/images/graemlins/heart.gif[/img]
Mahatma bets $1700. Hero calls.

River: ($5150) A[img]/images/graemlins/spade.gif[/img]
Mahatma goes all-in for $14587. Hero?