21517723172863 has 2 divisors, whose sum is σ = 21517723172864. Its totient is φ = 21517723172862.

The previous prime is 21517723172857. The next prime is 21517723172899. The reversal of 21517723172863 is 36827132771512.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21517723172863 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21517723172833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10758861586431 + 10758861586432.

It is an arithmetic number, because the mean of its divisors is an integer number (10758861586432).

Almost surely, 2^{21517723172863} is an apocalyptic number.

21517723172863 is a deficient number, since it is larger than the sum of its proper divisors (1).

21517723172863 is an equidigital number, since it uses as much as digits as its factorization.

21517723172863 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5927040, while the sum is 55.

The spelling of 21517723172863 in words is "twenty-one trillion, five hundred seventeen billion, seven hundred twenty-three million, one hundred seventy-two thousand, eight hundred sixty-three".