import math


def is_hexagonal(number):
    """
    Check given number to be a hexagonal number.

    :param number: value to be checked to be a hexagonal number.
    :returns: True when given value is a hexagonal number
    see http://en.wikipedia.org/wiki/Hexagonal_number

    >>> is_hexagonal(15)
    True
    >>> is_hexagonal(14)
    False
    """
    value = (math.sqrt(8 * number + 1) + 1) / 4.0
    return value == int(value)