20718868129 has 4 divisors (see below), whose sum is σ = 20720023684. Its totient is φ = 20717712576.

The previous prime is 20718868091. The next prime is 20718868139. The reversal of 20718868129 is 92186881702.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 92186881702 = 2 ⋅46093440851.

It can be written as a sum of positive squares in 2 ways, for example, as 12592206225 + 8126661904 = 112215^2 + 90148^2 .

It is a cyclic number.

It is not a de Polignac number, because 20718868129 - 2¹³ = 20718859937 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20718868139) 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 in 3 ways as a sum of consecutive naturals, for example, 550452 + ... + 586885.

It is an arithmetic number, because the mean of its divisors is an integer number (5180005921).

Almost surely, 2^20718868129 is an apocalyptic number.

It is an amenable number.

20718868129 is a deficient number, since it is larger than the sum of its proper divisors (1155555).

20718868129 is a wasteful number, since it uses less digits than its factorization.

20718868129 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1155554.

The product of its (nonzero) digits is 774144, while the sum is 52.

The spelling of 20718868129 in words is "twenty billion, seven hundred eighteen million, eight hundred sixty-eight thousand, one hundred twenty-nine".