Find least common multiple (C++)

#include <map>
#include <vector>
#include <cmath>

const int NUMBER = 20;

bool isPrime(int number);
int getNextPrime(int number);
std::map<int, int> getPrimeFactors(int number);
int getRangeLeastCommonMultiple(int maxNumber);

//This program finds the smallest number that is evenly divisible by all numbers from 1 to NUMBERS
int main()
{
    return getRangeLeastCommonMultiple(NUMBER);
}

bool isPrime(int number)
{
    if(number == 2)
    {
        return true;
    }
    else
    {
        for(int i=3; i<number; i+=2)
        {
            if(number %i == 0)
            {
                return false;
            }
        }
    }
    return true;
}

int getNextPrime(int number)
{
    do
    {
        ++number;
    } while(!isPrime(number));
    return number;
}

std::map<int, int> getPrimeFactors(int number)
{
    std::map<int, int> factors;
    for(int i=2; number>1; i=getNextPrime(i))
    {
        while(!(number%i))
        {
            number/=i;
            if(factors.find(i)==factors.end())
            {
                factors[i]=1;
            } else
            {
                ++(factors[i]);
            }
        }
    }
    return factors;
}

int getRangeLeastCommonMultiple(int maxNumber)
{
    //get the prime factor representations of all numbers from 2 to the max number
    std::vector<std::map<int,int>> primeFactorRepresentations;
        for(int i=2; i<=maxNumber; ++i)
    {
        primeFactorRepresentations.push_back(getPrimeFactors(i));
    }

    //get the highest exponent of each prime factor
    std::map<int, int> factorList;
    for(auto primeFactors = primeFactorRepresentations.begin();
        primeFactors != primeFactorRepresentations.end(); ++primeFactors)
    {
        for(auto factor = (*primeFactors).begin(); factor != (*primeFactors).end(); ++factor)
        {
            auto fac = factorList.find((*factor).first);
            if(fac == factorList.end())
            {
                factorList[(*factor).first] = (*factor).second;
            }
            else if((*factor).second > (*fac).second)
            {
                factorList[(*factor).first] = (*factor).second;
            }
        }
    }

    int evenDivNumber = 1;
        for(auto factor = factorList.begin(); factor!= factorList.end(); ++factor)
    {
        evenDivNumber *= std::pow((double) (*factor).first, (*factor).second);
    }
    return evenDivNumber;
}