1999871 has 2 divisors, whose sum is σ = 1999872. Its totient is φ = 1999870.

The previous prime is 1999867. The next prime is 1999889. The reversal of 1999871 is 1789991.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1999871 - 2² = 1999867 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1999891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 999935 + 999936.

It is an arithmetic number, because the mean of its divisors is an integer number (999936).

2^1999871 is an apocalyptic number.

1999871 is a deficient number, since it is larger than the sum of its proper divisors (1).

1999871 is an equidigital number, since it uses as much as digits as its factorization.

1999871 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 40824, while the sum is 44.

The square root of 1999871 is about 1414.1679532502. The cubic root of 1999871 is about 125.9893961010.

The spelling of 1999871 in words is "one million, nine hundred ninety-nine thousand, eight hundred seventy-one".