1989972871 has 2 divisors, whose sum is σ = 1989972872. Its totient is φ = 1989972870.

The previous prime is 1989972841. The next prime is 1989972917. The reversal of 1989972871 is 1782799891.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1989972871 - 2⁹ = 1989972359 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1989972841) 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, 994986435 + 994986436.

It is an arithmetic number, because the mean of its divisors is an integer number (994986436).

Almost surely, 2^1989972871 is an apocalyptic number.

1989972871 is a deficient number, since it is larger than the sum of its proper divisors (1).

1989972871 is an equidigital number, since it uses as much as digits as its factorization.

1989972871 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4572288, while the sum is 61.

The square root of 1989972871 is about 44609.1119727797. Note that the first 3 decimals coincide. The cubic root of 1989972871 is about 1257.8119561160.

The spelling of 1989972871 in words is "one billion, nine hundred eighty-nine million, nine hundred seventy-two thousand, eight hundred seventy-one".