309900809 has 2 divisors, whose sum is σ = 309900810. Its totient is φ = 309900808.

The previous prime is 309900797. The next prime is 309900817. The reversal of 309900809 is 908009903.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 269616400 + 40284409 = 16420^2 + 6347^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-309900809 is a prime.

It is a super-2 number, since 2×309900809² = 192077022837708962, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (309900839) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 154950404 + 154950405.

It is an arithmetic number, because the mean of its divisors is an integer number (154950405).

Almost surely, 2^309900809 is an apocalyptic number.

It is an amenable number.

309900809 is a deficient number, since it is larger than the sum of its proper divisors (1).

309900809 is an equidigital number, since it uses as much as digits as its factorization.

309900809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496, while the sum is 38.

The square root of 309900809 is about 17603.9998011815. Note that the first 3 decimals coincide. The cubic root of 309900809 is about 676.7177531325.

The spelling of 309900809 in words is "three hundred nine million, nine hundred thousand, eight hundred nine".