20665332817 has 2 divisors, whose sum is σ = 20665332818. Its totient is φ = 20665332816.

The previous prime is 20665332811. The next prime is 20665332929. The reversal of 20665332817 is 71823356602.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14971724881 + 5693607936 = 122359^2 + 75456^2 .

It is a cyclic number.

It is not a de Polignac number, because 20665332817 - 2¹¹ = 20665330769 is a prime.

It is not a weakly prime, because it can be changed into another prime (20665332811) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10332666408 + 10332666409.

It is an arithmetic number, because the mean of its divisors is an integer number (10332666409).

Almost surely, 2^20665332817 is an apocalyptic number.

It is an amenable number.

20665332817 is a deficient number, since it is larger than the sum of its proper divisors (1).

20665332817 is an equidigital number, since it uses as much as digits as its factorization.

20665332817 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 362880, while the sum is 43.

The spelling of 20665332817 in words is "twenty billion, six hundred sixty-five million, three hundred thirty-two thousand, eight hundred seventeen".