2121121217209 has 2 divisors, whose sum is σ = 2121121217210. Its totient is φ = 2121121217208.

The previous prime is 2121121217179. The next prime is 2121121217221. The reversal of 2121121217209 is 9027121211212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1547424042025 + 573697175184 = 1243955^2 + 757428^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121121217209 - 2⁷ = 2121121217081 is a prime.

It is not a weakly prime, because it can be changed into another prime (2121121217249) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1060560608604 + 1060560608605.

It is an arithmetic number, because the mean of its divisors is an integer number (1060560608605).

Almost surely, 2^{2121121217209} is an apocalyptic number.

It is an amenable number.

2121121217209 is a deficient number, since it is larger than the sum of its proper divisors (1).

2121121217209 is an equidigital number, since it uses as much as digits as its factorization.

2121121217209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2016, while the sum is 31.

The spelling of 2121121217209 in words is "two trillion, one hundred twenty-one billion, one hundred twenty-one million, two hundred seventeen thousand, two hundred nine".