999665389 has 2 divisors, whose sum is σ = 999665390. Its totient is φ = 999665388.

The previous prime is 999665357. The next prime is 999665473. The reversal of 999665389 is 983566999.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 921608164 + 78057225 = 30358^2 + 8835^2 .

It is a cyclic number.

It is not a de Polignac number, because 999665389 - 2⁵ = 999665357 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 999665389.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999665189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499832694 + 499832695.

It is an arithmetic number, because the mean of its divisors is an integer number (499832695).

Almost surely, 2^999665389 is an apocalyptic number.

It is an amenable number.

999665389 is a deficient number, since it is larger than the sum of its proper divisors (1).

999665389 is an equidigital number, since it uses as much as digits as its factorization.

999665389 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28343520, while the sum is 64.

The square root of 999665389 is about 31617.4854945804. The cubic root of 999665389 is about 999.8884505572. Note that the first 3 decimals are identical.

The spelling of 999665389 in words is "nine hundred ninety-nine million, six hundred sixty-five thousand, three hundred eighty-nine".