1999999871 has 2 divisors, whose sum is σ = 1999999872. Its totient is φ = 1999999870.

The previous prime is 1999999861. The next prime is 1999999873. The reversal of 1999999871 is 1789999991.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1999999871 is a prime.

Together with 1999999873, 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 = 1999999795 and 1999999804.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1999999873) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999999935 + 999999936.

It is an arithmetic number, because the mean of its divisors is an integer number (999999936).

Almost surely, 2^1999999871 is an apocalyptic number.

1999999871 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999999871 is an equidigital number, since it uses as much as digits as its factorization.

1999999871 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 29760696, while the sum is 71.

The square root of 1999999871 is about 44721.3581077319. The cubic root of 1999999871 is about 1259.9210228066.

The spelling of 1999999871 in words is "one billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred seventy-one".