20865980171 has 2 divisors, whose sum is σ = 20865980172. Its totient is φ = 20865980170.

The previous prime is 20865980143. The next prime is 20865980173. The reversal of 20865980171 is 17108956802.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20865980171 is a prime.

It is a Sophie Germain prime.

Together with 20865980173, 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 (20865980173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10432990085 + 10432990086.

It is an arithmetic number, because the mean of its divisors is an integer number (10432990086).

Almost surely, 2^20865980171 is an apocalyptic number.

20865980171 is a deficient number, since it is larger than the sum of its proper divisors (1).

20865980171 is an equidigital number, since it uses as much as digits as its factorization.

20865980171 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 241920, while the sum is 47.

The spelling of 20865980171 in words is "twenty billion, eight hundred sixty-five million, nine hundred eighty thousand, one hundred seventy-one".