18971971157 has 2 divisors, whose sum is σ = 18971971158. Its totient is φ = 18971971156.

The previous prime is 18971971141. The next prime is 18971971159. The reversal of 18971971157 is 75117917981.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10583059876 + 8388911281 = 102874^2 + 91591^2 .

It is a cyclic number.

It is not a de Polignac number, because 18971971157 - 2⁴ = 18971971141 is a prime.

Together with 18971971159, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18971971159) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9485985578 + 9485985579.

It is an arithmetic number, because the mean of its divisors is an integer number (9485985579).

Almost surely, 2^18971971157 is an apocalyptic number.

It is an amenable number.

18971971157 is a deficient number, since it is larger than the sum of its proper divisors (1).

18971971157 is an equidigital number, since it uses as much as digits as its factorization.

18971971157 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1111320, while the sum is 56.

The spelling of 18971971157 in words is "eighteen billion, nine hundred seventy-one million, nine hundred seventy-one thousand, one hundred fifty-seven".