999869989 has 2 divisors, whose sum is σ = 999869990. Its totient is φ = 999869988.

The previous prime is 999869957. The next prime is 999870017. The reversal of 999869989 is 989968999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 891022500 + 108847489 = 29850^2 + 10433^2 .

It is a cyclic number.

It is not a de Polignac number, because 999869989 - 2⁵ = 999869957 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (999869089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499934994 + 499934995.

It is an arithmetic number, because the mean of its divisors is an integer number (499934995).

Almost surely, 2^999869989 is an apocalyptic number.

It is an amenable number.

999869989 is a deficient number, since it is larger than the sum of its proper divisors (1).

999869989 is an equidigital number, since it uses as much as digits as its factorization.

999869989 is an evil number, because the sum of its binary digits is even.

The product of its digits is 204073344, while the sum is 76.

The square root of 999869989 is about 31620.7208804606. The cubic root of 999869989 is about 999.9566611218.

The spelling of 999869989 in words is "nine hundred ninety-nine million, eight hundred sixty-nine thousand, nine hundred eighty-nine".