It has been my observation that the number 7 in numerology is just as powerful as any of the so-called master numbers(such as 11 or 22). Many words or names reducing to this number carry an extremely powerful vibration that goes beyond the other common numbers. There are many reasons or this beginning with the obvious importance of this number in biblical scripture. Seven is a dominant number in both the old and new testaments of the bible from the 7 days of Creation to the 7 seals of the book of Revelation. Then there is the seven-day week and the seven traditional planets and aspects of astrology as well as the seven musical notes and colors, although all of these can be expanded to 12 which is an equally important number.
In numerology, 7 is considered a highly spiritual number with introverted qualities and is associated with the planet Neptune. I agree with the spirituial element, and to some extent with the introversion, but not with the planet association. Seven is an odd or masculine number whereas Neptune or Pisces-its ruling sign is an even or feminine number/influence. Just as the Sun or Leo is associated with the number 1, and the Moon or Cancer is associated with the number 2, so Uranus or Aquarius is 7(opposite on the wheel) and Saturn or Capricorn is 8(also opposite on the wheel).
Seven, the number of heaven, fits perfectly with Uranus the planet of heaven. Uranus is also the 7th planet from the Sun and takes 7 years to traverse each zodiac sign. It's exaltation is in Libra the 7th sign, just as the Sun's exaltation is in Aries the first sign(its opposite).
The number 7 is highly indivisible(mathematically), giving it much strength and originality. It is spiritual in the sense that it seeks and follows truth and concerns itself with the good of humanity. In the old schools of initiation, such as those of Pythagoras, candidates whose names or birthdays reduced to 7 were immediately accepted for training as they were considered to have a natural grasp or understanding of the higher laws of spirit.
Sevens are also prominent in the arts and entertainment fields where their powerful creativity and originality find a natural outlet. They can also be influential writers, speakers, or media people, bringing their truth to the masses. The downside of sevens is their almost complete lack of practical or business ability(also seen in 11's) which is where they need the help of a more worldly partner(such as a 4, 8, or 22).
The letters associated with 7 in numerology are G, P, and Y. G as in God, great, or good, P as in planet, peace, providence, and prosperity, an Y as in yin and yang, yod, and yearning. The ages are 7(childhood), 14(teenhood), and 21(adulthood).
The word seven contains the master letter v perfectly balanced in the middle of it also adding to its power(at least in the English language).
In this way, 7, 11, 22, and 33 or Uranus, Neptune, Pluto, and Eris(the "modern" planets), represent master vibrations in numerology.