21202205807917 has 2 divisors, whose sum is σ = 21202205807918. Its totient is φ = 21202205807916.

The previous prime is 21202205807899. The next prime is 21202205807953. The reversal of 21202205807917 is 71970850220212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12876822688041 + 8325383119876 = 3588429^2 + 2885374^2 .

It is a cyclic number.

It is not a de Polignac number, because 21202205807917 - 2²³ = 21202197419309 is a prime.

It is a super-3 number, since 3×21202205807917³ (a number of 41 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21202205807957) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601102903958 + 10601102903959.

It is an arithmetic number, because the mean of its divisors is an integer number (10601102903959).

Almost surely, 2^{21202205807917} is an apocalyptic number.

It is an amenable number.

21202205807917 is a deficient number, since it is larger than the sum of its proper divisors (1).

21202205807917 is an equidigital number, since it uses as much as digits as its factorization.

21202205807917 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 282240, while the sum is 46.

The spelling of 21202205807917 in words is "twenty-one trillion, two hundred two billion, two hundred five million, eight hundred seven thousand, nine hundred seventeen".