2120309 has 2 divisors, whose sum is σ = 2120310. Its totient is φ = 2120308.

The previous prime is 2120303. The next prime is 2120317. The reversal of 2120309 is 9030212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1697809 + 422500 = 1303^2 + 650^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2120309 is a prime.

It is a Sophie Germain prime.

It is an Ulam number.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2120303) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1060154 + 1060155.

It is an arithmetic number, because the mean of its divisors is an integer number (1060155).

2^2120309 is an apocalyptic number.

It is an amenable number.

2120309 is a deficient number, since it is larger than the sum of its proper divisors (1).

2120309 is an equidigital number, since it uses as much as digits as its factorization.

2120309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 2120309 is about 1456.1280850255. The cubic root of 2120309 is about 128.4694068388.

Subtracting 2120309 from its reverse (9030212), we obtain a triangular number (6909903 = T₃₇₁₇).

The spelling of 2120309 in words is "two million, one hundred twenty thousand, three hundred nine".