'p2 * p1 with p2 in the coefficient domain of p1.
Examples
>>> from sympy.polys.domains import ZZ
>>> from sympy.polys.rings import ring
>>> _, x, y = ring(\'x, y\', ZZ)
>>> p = x + y
>>> 4 * p
4*x + 4*y'

def __rmul__(p1, p2):

    p = p1.ring.zero
    if (not p2):
        return p
    try:
        p2 = p.ring.domain_new(p2)
    except CoercionFailed:
        return NotImplemented
    else:
        for (exp1, v1) in p1.items():
            v = (p2 * v1)
            if v:
                p[exp1] = v
        return p
