What is the Least Common Multiple of 21420 and 21440?

Least common multiple or lowest common denominator (lcd) can be calculated in two way; with the LCM formula calculation of greatest common factor (GCF), or multiplying the prime factors with the highest exponent factor.

Least Common Multiple of 21420 and 21440 with GCF Formula

The formula of LCM is LCM(a,b) = ( a × b) / GCF(a,b).
We need to calculate greatest common factor 21420 and 21440, than apply into the LCM equation.

GCF(21420,21440) = 20
LCM(21420,21440) = ( 21420 × 21440) / 20
LCM(21420,21440) = 459244800 / 20
LCM(21420,21440) = 22962240

Least Common Multiple (LCM) of 21420 and 21440 with Primes

Least common multiple can be found by multiplying the highest exponent prime factors of 21420 and 21440. First we will calculate the prime factors of 21420 and 21440.

Prime Factorization of 21420

Prime Factorization of 21440

Now multiplying the highest exponent prime factors to calculate the LCM of 21420 and 21440.

LCM(21420,21440) = 2⁶ × 3² × 5¹ × 7¹ × 17¹ × 67¹
LCM(21420,21440) = 22962240