20718315738877 has 2 divisors, whose sum is σ = 20718315738878. Its totient is φ = 20718315738876.

The previous prime is 20718315738871. The next prime is 20718315738881. The reversal of 20718315738877 is 77883751381702.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20532308125081 + 186007613796 = 4531259^2 + 431286^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20718315738877 is a prime.

It is a super-2 number, since 2×20718315738877² (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 (20718315738871) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10359157869438 + 10359157869439.

It is an arithmetic number, because the mean of its divisors is an integer number (10359157869439).

Almost surely, 2^{20718315738877} is an apocalyptic number.

It is an amenable number.

20718315738877 is a deficient number, since it is larger than the sum of its proper divisors (1).

20718315738877 is an equidigital number, since it uses as much as digits as its factorization.

20718315738877 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 110638080, while the sum is 67.

The spelling of 20718315738877 in words is "twenty trillion, seven hundred eighteen billion, three hundred fifteen million, seven hundred thirty-eight thousand, eight hundred seventy-seven".