1991100001 has 8 divisors (see below), whose sum is σ = 2177697600. Its totient is φ = 1805433840.

The previous prime is 1991099983. The next prime is 1991100017. The reversal of 1991100001 is 1000011991.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1991100001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1991100901) 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, 228381 + ... + 236938.

It is an arithmetic number, because the mean of its divisors is an integer number (272212200).

Almost surely, 2^1991100001 is an apocalyptic number.

1991100001 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

1991100001 is a deficient number, since it is larger than the sum of its proper divisors (186597599).

1991100001 is a wasteful number, since it uses less digits than its factorization.

1991100001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 465719.

The product of its (nonzero) digits is 81, while the sum is 22.

The square root of 1991100001 is about 44621.7435898688. The cubic root of 1991100001 is about 1258.0493881647.

Adding to 1991100001 its reverse (1000011991), we get a palindrome (2991111992).

It can be divided in two parts, 1991 and 100001, that multiplied together give a palindrome (199101991).

The spelling of 1991100001 in words is "one billion, nine hundred ninety-one million, one hundred thousand, one".