2021291809 has 2 divisors, whose sum is σ = 2021291810. Its totient is φ = 2021291808.

The previous prime is 2021291803. The next prime is 2021291827. The reversal of 2021291809 is 9081921202.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1681000000 + 340291809 = 41000^2 + 18447^2 .

It is a cyclic number.

It is not a de Polignac number, because 2021291809 - 2⁹ = 2021291297 is a prime.

It is not a weakly prime, because it can be changed into another prime (2021291803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1010645904 + 1010645905.

It is an arithmetic number, because the mean of its divisors is an integer number (1010645905).

Almost surely, 2^2021291809 is an apocalyptic number.

It is an amenable number.

2021291809 is a deficient number, since it is larger than the sum of its proper divisors (1).

2021291809 is an equidigital number, since it uses as much as digits as its factorization.

2021291809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 5184, while the sum is 34.

The square root of 2021291809 is about 44958.7789981000. The cubic root of 2021291809 is about 1264.3762768510.

The spelling of 2021291809 in words is "two billion, twenty-one million, two hundred ninety-one thousand, eight hundred nine".