20818306518623 has 2 divisors, whose sum is σ = 20818306518624. Its totient is φ = 20818306518622.

The previous prime is 20818306518509. The next prime is 20818306518637. The reversal of 20818306518623 is 32681560381802.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20818306518623 - 2¹⁸ = 20818306256479 is a prime.

It is a super-2 number, since 2×20818306518623² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20818306518223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10409153259311 + 10409153259312.

It is an arithmetic number, because the mean of its divisors is an integer number (10409153259312).

Almost surely, 2^{20818306518623} is an apocalyptic number.

20818306518623 is a deficient number, since it is larger than the sum of its proper divisors (1).

20818306518623 is an equidigital number, since it uses as much as digits as its factorization.

20818306518623 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3317760, while the sum is 53.

The spelling of 20818306518623 in words is "twenty trillion, eight hundred eighteen billion, three hundred six million, five hundred eighteen thousand, six hundred twenty-three".