20965881617 has 2 divisors, whose sum is σ = 20965881618. Its totient is φ = 20965881616.

The previous prime is 20965881593. The next prime is 20965881619. The reversal of 20965881617 is 71618856902.

It is a Cunningham number, because it is equal to 144796²+1.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20965881616 + 1 = 144796^2 + 1^2 .

It is a cyclic number.

It is not a de Polignac number, because 20965881617 - 2⁸ = 20965881361 is a prime.

Together with 20965881619, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20965881619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10482940808 + 10482940809.

It is an arithmetic number, because the mean of its divisors is an integer number (10482940809).

Almost surely, 2^20965881617 is an apocalyptic number.

It is an amenable number.

20965881617 is a deficient number, since it is larger than the sum of its proper divisors (1).

20965881617 is an equidigital number, since it uses as much as digits as its factorization.

20965881617 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1451520, while the sum is 53.

The spelling of 20965881617 in words is "twenty billion, nine hundred sixty-five million, eight hundred eighty-one thousand, six hundred seventeen".