20664383357509 has 2 divisors, whose sum is σ = 20664383357510. Its totient is φ = 20664383357508.

The previous prime is 20664383357491. The next prime is 20664383357543. The reversal of 20664383357509 is 90575338346602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19195596913284 + 1468786444225 = 4381278^2 + 1211935^2 .

It is a cyclic number.

It is not a de Polignac number, because 20664383357509 - 2⁵ = 20664383357477 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20664383357549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10332191678754 + 10332191678755.

It is an arithmetic number, because the mean of its divisors is an integer number (10332191678755).

Almost surely, 2^{20664383357509} is an apocalyptic number.

It is an amenable number.

20664383357509 is a deficient number, since it is larger than the sum of its proper divisors (1).

20664383357509 is an equidigital number, since it uses as much as digits as its factorization.

20664383357509 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 97977600, while the sum is 61.

The spelling of 20664383357509 in words is "twenty trillion, six hundred sixty-four billion, three hundred eighty-three million, three hundred fifty-seven thousand, five hundred nine".