2128309 has 2 divisors, whose sum is σ = 2128310. Its totient is φ = 2128308.

The previous prime is 2128303. The next prime is 2128319. The reversal of 2128309 is 9038212.

2128309 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1822500 + 305809 = 1350^2 + 553^2 .

It is a cyclic number.

It is not a de Polignac number, because 2128309 - 2¹⁹ = 1604021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2128303) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1064154 + 1064155.

It is an arithmetic number, because the mean of its divisors is an integer number (1064155).

2^2128309 is an apocalyptic number.

It is an amenable number.

2128309 is a deficient number, since it is larger than the sum of its proper divisors (1).

2128309 is an equidigital number, since it uses as much as digits as its factorization.

2128309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 2128309 is about 1458.8725098514. The cubic root of 2128309 is about 128.6307772447.

Subtracting 2128309 from its reverse (9038212), we obtain a triangular number (6909903 = T₃₇₁₇).

The spelling of 2128309 in words is "two million, one hundred twenty-eight thousand, three hundred nine".