21573698017 has 2 divisors, whose sum is σ = 21573698018. Its totient is φ = 21573698016.

The previous prime is 21573697967. The next prime is 21573698021. The reversal of 21573698017 is 71089637512.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16108940241 + 5464757776 = 126921^2 + 73924^2 .

It is a cyclic number.

It is not a de Polignac number, because 21573698017 - 2⁷ = 21573697889 is a prime.

It is a super-2 number, since 2×21573698017² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21573698417) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10786849008 + 10786849009.

It is an arithmetic number, because the mean of its divisors is an integer number (10786849009).

Almost surely, 2^21573698017 is an apocalyptic number.

It is an amenable number.

21573698017 is a deficient number, since it is larger than the sum of its proper divisors (1).

21573698017 is an equidigital number, since it uses as much as digits as its factorization.

21573698017 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 635040, while the sum is 49.

The spelling of 21573698017 in words is "twenty-one billion, five hundred seventy-three million, six hundred ninety-eight thousand, seventeen".