21033011309 has 2 divisors, whose sum is σ = 21033011310. Its totient is φ = 21033011308.

The previous prime is 21033011287. The next prime is 21033011317. The reversal of 21033011309 is 90311033012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11413717225 + 9619294084 = 106835^2 + 98078^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21033011309 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21033011359) 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, 10516505654 + 10516505655.

It is an arithmetic number, because the mean of its divisors is an integer number (10516505655).

Almost surely, 2^21033011309 is an apocalyptic number.

It is an amenable number.

21033011309 is a deficient number, since it is larger than the sum of its proper divisors (1).

21033011309 is an equidigital number, since it uses as much as digits as its factorization.

21033011309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 486, while the sum is 23.

The spelling of 21033011309 in words is "twenty-one billion, thirty-three million, eleven thousand, three hundred nine".