1001009999 has 16 divisors (see below), whose sum is σ = 1101081600. Its totient is φ = 902484000.

The previous prime is 1001009987. The next prime is 1001010011. The reversal of 1001009999 is 9999001001.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1001009987) and next prime (1001010011).

It is not a de Polignac number, because 1001009999 - 2⁴ = 1001009983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1001009099) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 942929 + ... + 943989.

It is an arithmetic number, because the mean of its divisors is an integer number (68817600).

Almost surely, 2^1001009999 is an apocalyptic number.

1001009999 is a deficient number, since it is larger than the sum of its proper divisors (100071601).

1001009999 is a wasteful number, since it uses less digits than its factorization.

1001009999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1702.

The product of its (nonzero) digits is 6561, while the sum is 38.

The square root of 1001009999 is about 31638.7420578000. The cubic root of 1001009999 is about 1000.3365530527.

The spelling of 1001009999 in words is "one billion, one million, nine thousand, nine hundred ninety-nine".