21717181612673 has 2 divisors, whose sum is σ = 21717181612674. Its totient is φ = 21717181612672.

The previous prime is 21717181612589. The next prime is 21717181612739. The reversal of 21717181612673 is 37621618171712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20579360456704 + 1137821155969 = 4536448^2 + 1066687^2 .

It is a cyclic number.

It is not a de Polignac number, because 21717181612673 - 2⁸ = 21717181612417 is a prime.

It is not a weakly prime, because it can be changed into another prime (21717181602673) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10858590806336 + 10858590806337.

It is an arithmetic number, because the mean of its divisors is an integer number (10858590806337).

Almost surely, 2^{21717181612673} is an apocalyptic number.

It is an amenable number.

21717181612673 is a deficient number, since it is larger than the sum of its proper divisors (1).

21717181612673 is an equidigital number, since it uses as much as digits as its factorization.

21717181612673 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1185408, while the sum is 53.

The spelling of 21717181612673 in words is "twenty-one trillion, seven hundred seventeen billion, one hundred eighty-one million, six hundred twelve thousand, six hundred seventy-three".