Mega Nihilego
Rock/Poison
Ability: Levitate
HP: 109
Atk: 53
Def: 67 (+20)
Spa: 167 (+40)
Spd: 137 (+6)
Spe: 137 (+34)

Mega Buzzwole
Bug/Fighting
Ability: Triage
HP: 107
Atk: 179 (+40)
Def: 179 (+40)
Spa: 53
Spd: 73 (+20)
Spe: 79

Mega Pheromosa
Bug/Fighting
Ability: Queenly Majesty
HP: 71
Atk: 167 (+30)
Def: 43 (+6)
Spa: 167 (+30)
Spd: 43 (+6)
Spe: 179 (+28)

Mega Xurkitree
Electric/Grass
Ability: Simple
HP: 83
Atk: 89
Def: 101 (+30)
Spa: 193 (+20)
Spd: 101 (+30)
Spe: 103 (+20)

Mega Kartana
Grass/Steel
Ability: Steelworker
HP: 59
Atk: 211 (+30)
Def: 151 (+20)
Spa: 59
Spd: 59 (+28)
Spe: 131 (+22)

Mega Celesteela
Steel/Flying
Ability: Flash Fire
HP: 97
Atk: 127 (+26)
Def: 127 (+24)
Spa: 131 (+24)
Spd: 127 (+26)
Spe: 61

Mega Guzzlord
Dark/Dragon
Ability: Filter
HP: 223
Atk: 139 (+38)
Def: 103 (+50)
Spa: 97
Spd: 103 (+50)
Spe: 5 (-38)

Yes, these are all prime numbers.