2121212121209 has 6 divisors (see below), whose sum is σ = 2128476547806. Its totient is φ = 2113972403840.

The previous prime is 2121212121181. The next prime is 2121212121233. The reversal of 2121212121209 is 9021212121212.

It can be written as a sum of positive squares in 3 ways, for example, as 1029494329600 + 1091717791609 = 1014640^2 + 1044853^2 .

It is not a de Polignac number, because 2121212121209 - 2¹⁶ = 2121212055673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2121217121209) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12268472 + ... + 12440169.

It is an arithmetic number, because the mean of its divisors is an integer number (354746091301).

Almost surely, 2^{2121212121209} is an apocalyptic number.

It is an amenable number.

2121212121209 is a deficient number, since it is larger than the sum of its proper divisors (7264426597).

2121212121209 is an frugal number, since it uses more digits than its factorization.

2121212121209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24709227 (or 24708934 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 26.

The spelling of 2121212121209 in words is "two trillion, one hundred twenty-one billion, two hundred twelve million, one hundred twenty-one thousand, two hundred nine".