100991009 has 6 divisors (see below), whose sum is σ = 117479394. Its totient is φ = 86563680.

The previous prime is 100990979. The next prime is 100991041. The reversal of 100991009 is 900199001.

It can be written as a sum of positive squares in only one way, i.e., 95491984 + 5499025 = 9772^2 + 2345^2 .

It is not a de Polignac number, because 100991009 - 2²⁴ = 84213793 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (100991069) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1030472 + ... + 1030569.

It is an arithmetic number, because the mean of its divisors is an integer number (19579899).

Almost surely, 2^100991009 is an apocalyptic number.

It is an amenable number.

100991009 is a deficient number, since it is larger than the sum of its proper divisors (16488385).

100991009 is an equidigital number, since it uses as much as digits as its factorization.

100991009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2061055 (or 2061048 counting only the distinct ones).

The product of its (nonzero) digits is 729, while the sum is 29.

The square root of 100991009 is about 10049.4282921965. The cubic root of 100991009 is about 465.6871315015.

The spelling of 100991009 in words is "one hundred million, nine hundred ninety-one thousand, nine".