20661243313 has 2 divisors, whose sum is σ = 20661243314. Its totient is φ = 20661243312.

The previous prime is 20661243277. The next prime is 20661243329. The reversal of 20661243313 is 31334216602.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20607176704 + 54066609 = 143552^2 + 7353^2 .

It is a cyclic number.

It is not a de Polignac number, because 20661243313 - 2¹³ = 20661235121 is a prime.

It is not a weakly prime, because it can be changed into another prime (20661253313) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10330621656 + 10330621657.

It is an arithmetic number, because the mean of its divisors is an integer number (10330621657).

Almost surely, 2^20661243313 is an apocalyptic number.

It is an amenable number.

20661243313 is a deficient number, since it is larger than the sum of its proper divisors (1).

20661243313 is an equidigital number, since it uses as much as digits as its factorization.

20661243313 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15552, while the sum is 31.

Adding to 20661243313 its reverse (31334216602), we get a palindrome (51995459915).

The spelling of 20661243313 in words is "twenty billion, six hundred sixty-one million, two hundred forty-three thousand, three hundred thirteen".