1001009991 has 8 divisors (see below), whose sum is σ = 1335090544. Its totient is φ = 667134720.

The previous prime is 1001009987. The next prime is 1001010011. The reversal of 1001009991 is 1999001001.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1001009991 - 2² = 1001009987 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 (1001009941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39556 + ... + 59721.

It is an arithmetic number, because the mean of its divisors is an integer number (166886318).

Almost surely, 2^1001009991 is an apocalyptic number.

1001009991 is a deficient number, since it is larger than the sum of its proper divisors (334080553).

1001009991 is an equidigital number, since it uses as much as digits as its factorization.

1001009991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 102641.

The product of its (nonzero) digits is 729, while the sum is 30.

The square root of 1001009991 is about 31638.7419313727. The cubic root of 1001009991 is about 1000.3365503878.

The spelling of 1001009991 in words is "one billion, one million, nine thousand, nine hundred ninety-one".