• 2 can be written using four 4's:
The next prime is 3.
It is the 3-rd Fibonacci number F3.
It is a primorial, being the product of the first 1 primes.
It is a double factorial (2 = 2 !! = 2 ).
2 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.
2 is an esthetic number in base 2, because in such base its adjacent digits differ by 1.
2 is a sliding number.
It is a tau number, because it is divible by the number of its divisors (2).
It is the 2-nd Motzkin number.
It is a cyclic number.
It is the 2-nd Bell number.
It is the 2-nd Catalan number.
It is a Sophie Germain prime.
It is a Chen prime.
It is a super Niven number, because it is divisible the sum of any subset of its (nonzero) digits.
It is an iccanobiF number.
2 is an idoneal number.
It is a tribonacci number.
It is a tetranacci number.
It is an Ulam number.
It is a Kynea number, being equal to (20 + 1)2 - 2.
2 is strictly pandigital in base 2.
It is the 2-nd Perrin number.
It is a Curzon number.
It is a nialpdrome in base 2.
It is a self number, because there is not a number n which added to its sum of digits gives 2.
It is a panconsummate number.
2 is an untouchable number, because it is not equal to the sum of proper divisors of any number.
It is a subfactorial, being equal to the number of derangements of 3 objects .
It is a good prime.
It is a Pierpont prime, being equal to 20 ⋅ 30 + 1.
It is an impolite number, since it cannot be written as a nontrivial sum of consecutive naturals.
It is a (trivial) narcissistic number.
2 is a highly composite number, because it has more divisors than any smaller number.
2 is a superabundant number, because it has a larger abundancy index than any smaller number.
It is a practical number, because each smaller number is the sum of distinct divisors of 2
2 is an equidigital number, since it uses as much as digits as its factorization.
2 is an odious number, because the sum of its binary digits is odd.
The square root of 2 is about 1.4142135624. The cubic root of 2 is about 1.2599210499.