101

101 (one hundred [and] one) is the natural number following 100 and preceding 102. It is variously pronounced "one hundred and one" / "a hundred and one", "one hundred one" / "a hundred one", and "one oh one". As an ordinal number, 101st (one hundred [and] first), rather than 101th, is the correct form. In mathematics 101 is: the 26th prime number and the smallest above 100. a palindromic number in decimal, and so a palindromic prime. a Chen prime since 103 is also prime, with which it makes a twin prime pair. a sexy prime since 107 and 113 are also prime, with which it makes a sexy prime triplet. a unique prime because the period length of its reciprocal is unique among primes. an Eisenstein prime with no imaginary part and real part of the form . the fifth alternating factorial. a centered decagonal number. the only existing prime with alternating 1s and 0s in decimal and the largest known prime of the form . the number of compositions of 12 into distinct parts. the smallest number that can be expressed as the sum of three distinct nonzero squares in more than two ways: , or (see image).