999638009 has 2 divisors, whose sum is σ = 999638010. Its totient is φ = 999638008.

The previous prime is 999637993. The next prime is 999638023. The reversal of 999638009 is 900836999.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 944209984 + 55428025 = 30728^2 + 7445^2 .

It is a cyclic number.

It is not a de Polignac number, because 999638009 - 2⁴ = 999637993 is a prime.

It is a super-2 number, since 2×999638009² = 1998552298074968162, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (999638069) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 499819004 + 499819005.

It is an arithmetic number, because the mean of its divisors is an integer number (499819005).

Almost surely, 2^999638009 is an apocalyptic number.

It is an amenable number.

999638009 is a deficient number, since it is larger than the sum of its proper divisors (1).

999638009 is an equidigital number, since it uses as much as digits as its factorization.

999638009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 944784, while the sum is 53.

The square root of 999638009 is about 31617.0525033565. The cubic root of 999638009 is about 999.8793217707.

The spelling of 999638009 in words is "nine hundred ninety-nine million, six hundred thirty-eight thousand, nine".