digplanet beta 1: Athena
Share digplanet:

Agriculture

Applied sciences

Arts

Belief

Chronology

Culture

Education

Environment

Geography

Health

History

Humanities

Language

Law

Life

Mathematics

Nature

People

Politics

Science

Society

Technology

 ← 120 121 122 →
Cardinal one hundred and twenty-one
Ordinal 121st
(one hundred and twenty-first)
Factorization 112
Divisors 1, 11, 121
Roman numeral CXXI
Binary 11110012
Ternary 111113
Quaternary 13214
Octal 1718
Duodecimal A112
Vigesimal 6120
Base 36 3D36

121 (one hundred [and] twenty-one) is the natural number following 120 and preceding 122.

## In mathematics

One hundred [and] 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). Other such squares must have at least 35 digits.

There are only two other squares known to be of the form n! + 1, supporting Brocard's conjecture. Another example of 121 being of the few examples supporting a conjecture is that Fermat conjectured that 4 and 121 are the only perfect squares of the form x3 - 4 (with x being 2 and 5, respectively).[1]

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

A Chinese checkers board has 121 holes

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 (11^2). But it can not be expressed as the sum of any other number plus that number's digits, making 121 a self number.

121 is also:

## References

1. ^ Wells, D., The Penguin Dictionary of Curious and Interesting Numbers, London: Penguin Group. (1987): 136
2. ^ Vodafone, Calling and messaging
3. ^ Rule 1.1, American Cribbage Congress, retrieved 6 September 2011

Original courtesy of Wikipedia: http://en.wikipedia.org/wiki/121_(number) — Please support Wikipedia.
A portion of the proceeds from advertising on Digplanet goes to supporting Wikipedia.
 1000000 videos foundNext >
 1000000 videos foundNext >
 1 news items
 ‚Alltagslärm' beeinflusst die Herzratenvariabilität innovations report Thu, 02 May 2013 01:07:03 -0700 Original-Publikation: Kraus, U. et al. (2013), Individual Day-Time Noise Exposure during Routine Activities and Heart Rate Variability in Adults: A Repeated Measures Study, Environmental Health Perspectives, Volume 121, Number 5, 607 - 612. Link zur ...
 Limit to books that you can completely read online Include partial books (book previews) .gsc-branding { display:block; }

Oops, we seem to be having trouble contacting Twitter