1989666899 has 4 divisors (see below), whose sum is σ = 2170545720. Its totient is φ = 1808788080.

The previous prime is 1989666863. The next prime is 1989666923. The reversal of 1989666899 is 9986669891.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1989666899 - 2²⁰ = 1988618323 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1989656899) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 90439394 + ... + 90439415.

It is an arithmetic number, because the mean of its divisors is an integer number (542636430).

Almost surely, 2^1989666899 is an apocalyptic number.

1989666899 is a deficient number, since it is larger than the sum of its proper divisors (180878821).

1989666899 is a wasteful number, since it uses less digits than its factorization.

1989666899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 180878820.

The product of its digits is 90699264, while the sum is 71.

The square root of 1989666899 is about 44605.6823622282. The cubic root of 1989666899 is about 1257.7474870685.

The spelling of 1989666899 in words is "one billion, nine hundred eighty-nine million, six hundred sixty-six thousand, eight hundred ninety-nine".