2121012809 has 2 divisors, whose sum is σ = 2121012810. Its totient is φ = 2121012808.

The previous prime is 2121012791. The next prime is 2121012811. The reversal of 2121012809 is 9082101212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1546691584 + 574321225 = 39328^2 + 23965^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121012809 - 2¹² = 2121008713 is a prime.

Together with 2121012811, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (2121012899) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1060506404 + 1060506405.

It is an arithmetic number, because the mean of its divisors is an integer number (1060506405).

Almost surely, 2^2121012809 is an apocalyptic number.

It is an amenable number.

2121012809 is a deficient number, since it is larger than the sum of its proper divisors (1).

2121012809 is an equidigital number, since it uses as much as digits as its factorization.

2121012809 is an evil number, because the sum of its binary digits is even.

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

The square root of 2121012809 is about 46054.4548225250. The cubic root of 2121012809 is about 1284.8361984933.

The spelling of 2121012809 in words is "two billion, one hundred twenty-one million, twelve thousand, eight hundred nine".