21313231309 has 2 divisors, whose sum is σ = 21313231310. Its totient is φ = 21313231308.

The previous prime is 21313231297. The next prime is 21313231343. The reversal of 21313231309 is 90313231312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10853055684 + 10460175625 = 104178^2 + 102275^2 .

It is a cyclic number.

It is not a de Polignac number, because 21313231309 - 2¹³ = 21313223117 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21313231369) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10656615654 + 10656615655.

It is an arithmetic number, because the mean of its divisors is an integer number (10656615655).

Almost surely, 2^21313231309 is an apocalyptic number.

It is an amenable number.

21313231309 is a deficient number, since it is larger than the sum of its proper divisors (1).

21313231309 is an equidigital number, since it uses as much as digits as its factorization.

21313231309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2916, while the sum is 28.

The spelling of 21313231309 in words is "twenty-one billion, three hundred thirteen million, two hundred thirty-one thousand, three hundred nine".