100000991 has 8 divisors (see below), whose sum is σ = 100745904. Its totient is φ = 99259200.

The previous prime is 100000969. The next prime is 100001029. The reversal of 100000991 is 199000001.

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

It is a cyclic number.

It is not a de Polignac number, because 100000991 - 2¹⁴ = 99984607 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 (100000921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 136061 + ... + 136793.

It is an arithmetic number, because the mean of its divisors is an integer number (12593238).

Almost surely, 2^100000991 is an apocalyptic number.

100000991 is a deficient number, since it is larger than the sum of its proper divisors (744913).

100000991 is an equidigital number, since it uses as much as digits as its factorization.

100000991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1561.

The product of its (nonzero) digits is 81, while the sum is 20.

The square root of 100000991 is about 10000.0495498772. The cubic root of 100000991 is about 464.1604166277.

Adding to 100000991 its reverse (199000001), we get a palindrome (299000992).

The spelling of 100000991 in words is "one hundred million, nine hundred ninety-one", and thus it is an aban number.