21001000309 has 2 divisors, whose sum is σ = 21001000310. Its totient is φ = 21001000308.

The previous prime is 21001000259. The next prime is 21001000343. The reversal of 21001000309 is 90300010012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20996879409 + 4120900 = 144903^2 + 2030^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001000309 - 2²¹ = 20998903157 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21001000292 and 21001000301.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001000369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500500154 + 10500500155.

It is an arithmetic number, because the mean of its divisors is an integer number (10500500155).

Almost surely, 2^21001000309 is an apocalyptic number.

It is an amenable number.

21001000309 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001000309 is an equidigital number, since it uses as much as digits as its factorization.

21001000309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54, while the sum is 16.

The spelling of 21001000309 in words is "twenty-one billion, one million, three hundred nine", and thus it is an aban number.