121 is the natural number following 120 and preceding 122.

In mathematics

One hundred ^* twenty-one is a square and is the sum of three consecutive primes (37 + 41 + 43). There are no squares besides 121 known to be of the form $1\; +\; p\; +\; p^2\; +\; p^3\; +\; p^4$, where p is prime (3, in this case). There are only two other squares known to be of the form n! + 1.

It is also a star number and a centered octagonal number.

In base 10, it is a Smith number since its digits add up to the same value as its factorization (which uses the same digits) and as a consequence of that it is a Friedman number. But it can not be expressed as the sum of any other number plus that number's digits, making 121 a self number.

In other fields

One hundred ^* twenty-one is also:

• The number for voicemail for mobile phones on the Vodafone network
• The Lockheed EC-121 Warning Star
• The year AD 121 or 121 BC.
• The number of points required to win a standard game of cribbage.
• The total number of days in the first four months of a leap year.

External links

• The web-address to the company one to one ab.

Integers

121 (nombre) | 121 | 121 | 121 (число) | 121 (število) | 121