19886978171 has 2 divisors, whose sum is σ = 19886978172. Its totient is φ = 19886978170.

The previous prime is 19886978149. The next prime is 19886978173. The reversal of 19886978171 is 17187968891.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 19886978171 - 2²² = 19882783867 is a prime.

Together with 19886978173, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 19886978098 and 19886978107.

It is not a weakly prime, because it can be changed into another prime (19886978173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9943489085 + 9943489086.

It is an arithmetic number, because the mean of its divisors is an integer number (9943489086).

Almost surely, 2^19886978171 is an apocalyptic number.

19886978171 is a deficient number, since it is larger than the sum of its proper divisors (1).

19886978171 is an equidigital number, since it uses as much as digits as its factorization.

19886978171 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12192768, while the sum is 65.

The spelling of 19886978171 in words is "nineteen billion, eight hundred eighty-six million, nine hundred seventy-eight thousand, one hundred seventy-one".