21020332309 has 2 divisors, whose sum is σ = 21020332310. Its totient is φ = 21020332308.

The previous prime is 21020332297. The next prime is 21020332331. The reversal of 21020332309 is 90323302012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16355852100 + 4664480209 = 127890^2 + 68297^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020332309 - 2¹⁹ = 21019808021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21020332369) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510166154 + 10510166155.

It is an arithmetic number, because the mean of its divisors is an integer number (10510166155).

Almost surely, 2^21020332309 is an apocalyptic number.

It is an amenable number.

21020332309 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020332309 is an equidigital number, since it uses as much as digits as its factorization.

21020332309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1944, while the sum is 25.

The spelling of 21020332309 in words is "twenty-one billion, twenty million, three hundred thirty-two thousand, three hundred nine".