21001231202309 has 2 divisors, whose sum is σ = 21001231202310. Its totient is φ = 21001231202308.

The previous prime is 21001231202291. The next prime is 21001231202317. The reversal of 21001231202309 is 90320213210012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17882199700225 + 3119031502084 = 4228735^2 + 1766078^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001231202309 - 2²⁸ = 21000962766853 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001131202309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500615601154 + 10500615601155.

It is an arithmetic number, because the mean of its divisors is an integer number (10500615601155).

Almost surely, 2^{21001231202309} is an apocalyptic number.

It is an amenable number.

21001231202309 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001231202309 is an equidigital number, since it uses as much as digits as its factorization.

21001231202309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1296, while the sum is 26.

The spelling of 21001231202309 in words is "twenty-one trillion, one billion, two hundred thirty-one million, two hundred two thousand, three hundred nine".