1689999989 has 2 divisors, whose sum is σ = 1689999990. Its totient is φ = 1689999988.

The previous prime is 1689999959. The next prime is 1690000021. The reversal of 1689999989 is 9899999861.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1229554225 + 460445764 = 35065^2 + 21458^2 .

It is a cyclic number.

It is not a de Polignac number, because 1689999989 - 2²⁰ = 1688951413 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1689999919) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 844999994 + 844999995.

It is an arithmetic number, because the mean of its divisors is an integer number (844999995).

Almost surely, 2^1689999989 is an apocalyptic number.

It is an amenable number.

1689999989 is a deficient number, since it is larger than the sum of its proper divisors (1).

1689999989 is an equidigital number, since it uses as much as digits as its factorization.

1689999989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 204073344, while the sum is 77.

The square root of 1689999989 is about 41109.6094484003. The cubic root of 1689999989 is about 1191.1384226121.

The spelling of 1689999989 in words is "one billion, six hundred eighty-nine million, nine hundred ninety-nine thousand, nine hundred eighty-nine".