1991189111001 has 8 divisors (see below), whose sum is σ = 2654956256640. Its totient is φ = 1327440686352.

The previous prime is 1991189110979. The next prime is 1991189111027. The reversal of 1991189111001 is 1001119811991.

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

It is not a de Polignac number, because 1991189111001 - 2⁷ = 1991189110873 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1991189111101) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4430161 + ... + 4858878.

It is an arithmetic number, because the mean of its divisors is an integer number (331869532080).

Almost surely, 2^{1991189111001} is an apocalyptic number.

It is an amenable number.

1991189111001 is a deficient number, since it is larger than the sum of its proper divisors (663767145639).

1991189111001 is an equidigital number, since it uses as much as digits as its factorization.

1991189111001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9360495.

The product of its (nonzero) digits is 5832, while the sum is 42.

The spelling of 1991189111001 in words is "one trillion, nine hundred ninety-one billion, one hundred eighty-nine million, one hundred eleven thousand, one".